diff --git a/frontend/src/components/CoverageSummaryCard.tsx b/frontend/src/components/CoverageSummaryCard.tsx
index b5279b7..3a074de 100644
--- a/frontend/src/components/CoverageSummaryCard.tsx
+++ b/frontend/src/components/CoverageSummaryCard.tsx
@@ -1,4 +1,5 @@
 import type { ReactNode } from "react";
+import MetricTooltip from "./MetricTooltip";
 
 interface CoverageSummaryCardProps {
   title: string;
@@ -7,6 +8,8 @@ interface CoverageSummaryCardProps {
   icon: ReactNode;
   colorClass: string;
   bgClass: string;
+  /** Optional tooltip explaining this metric to non-technical users */
+  tooltip?: { description: string; context?: string };
 }
 
 export default function CoverageSummaryCard({
@@ -16,6 +19,7 @@ export default function CoverageSummaryCard({
   icon,
   colorClass,
   bgClass,
+  tooltip,
 }: CoverageSummaryCardProps) {
   const percentage = total && total > 0 ? ((value / total) * 100).toFixed(1) : null;
 
@@ -23,7 +27,16 @@ export default function CoverageSummaryCard({
     <div className={`rounded-xl border border-gray-800 ${bgClass} p-5`}>
       <div className="flex items-center justify-between">
         <div>
-          <p className="text-sm font-medium text-gray-400">{title}</p>
+          <p className="text-sm font-medium text-gray-400 flex items-center">
+            {title}
+            {tooltip && (
+              <MetricTooltip
+                title={title}
+                description={tooltip.description}
+                context={tooltip.context}
+              />
+            )}
+          </p>
           <p className={`mt-1 text-3xl font-bold ${colorClass}`}>{value}</p>
           {percentage !== null && (
             <p className="mt-1 text-xs text-gray-500">{percentage}% of total</p>
diff --git a/frontend/src/components/MetricTooltip.tsx b/frontend/src/components/MetricTooltip.tsx
new file mode 100644
index 0000000..3e1b4c0
--- /dev/null
+++ b/frontend/src/components/MetricTooltip.tsx
@@ -0,0 +1,58 @@
+/**
+ * MetricTooltip — a small ⓘ icon that shows a plain-language explanation
+ * of a metric on hover. Designed for executive dashboards where not everyone
+ * knows what "MTTD" or "partial coverage" means.
+ */
+
+interface MetricTooltipProps {
+  title: string;
+  description: string;
+  /** Optional extra context line (e.g. "Why it matters") */
+  context?: string;
+  /** Positioning hint — defaults to 'below' */
+  position?: "below" | "above" | "left";
+}
+
+export default function MetricTooltip({
+  title,
+  description,
+  context,
+  position = "below",
+}: MetricTooltipProps) {
+  const posClass =
+    position === "above"
+      ? "bottom-full mb-2 left-0"
+      : position === "left"
+      ? "right-full mr-2 top-0"
+      : "top-full mt-2 left-0";
+
+  return (
+    <span className="relative group inline-flex items-center ml-1.5 align-middle">
+      {/* The ⓘ icon */}
+      <span className="flex h-4 w-4 cursor-help items-center justify-center rounded-full border border-gray-600 bg-gray-800 text-[9px] font-bold text-gray-400 hover:border-cyan-500/50 hover:text-cyan-400 transition-colors select-none">
+        i
+      </span>
+
+      {/* Tooltip panel */}
+      <span
+        className={`
+          pointer-events-none absolute ${posClass} z-50 w-64
+          rounded-xl border border-gray-700 bg-gray-900 p-3 shadow-xl
+          opacity-0 transition-opacity duration-150 group-hover:opacity-100
+        `}
+      >
+        {/* Arrow */}
+        {position !== "above" && position !== "left" && (
+          <span className="absolute bottom-full left-3 border-4 border-transparent border-b-gray-700" />
+        )}
+        <p className="mb-1.5 text-xs font-semibold text-white">{title}</p>
+        <p className="text-[11px] leading-snug text-gray-300">{description}</p>
+        {context && (
+          <p className="mt-1.5 text-[10px] leading-snug text-cyan-400/80 border-t border-gray-800 pt-1.5">
+            {context}
+          </p>
+        )}
+      </span>
+    </span>
+  );
+}
diff --git a/frontend/src/pages/DashboardPage.tsx b/frontend/src/pages/DashboardPage.tsx
index b982bc9..0217992 100644
--- a/frontend/src/pages/DashboardPage.tsx
+++ b/frontend/src/pages/DashboardPage.tsx
@@ -42,6 +42,7 @@ import {
 import { getCoverageEvolution } from "../api/snapshots";
 import CoverageSummaryCard from "../components/CoverageSummaryCard";
 import TacticCoverageChart from "../components/TacticCoverageChart";
+import MetricTooltip from "../components/MetricTooltip";
 import type { TestState } from "../types/models";
 
 /* ── Badge colours (reused from TestsPage) ─────────────────────────── */
@@ -199,6 +200,7 @@ export default function DashboardPage() {
             icon={<Shield className="h-6 w-6 text-cyan-400" />}
             colorClass="text-cyan-400"
             bgClass="bg-gray-900"
+            tooltip={{ description: "Total number of MITRE ATT&CK attack techniques tracked in the platform. This is the full universe of known attack methods we measure coverage against.", context: "A higher total means broader threat visibility." }}
           />
           <CoverageSummaryCard
             title="Validated"
@@ -207,6 +209,7 @@ export default function DashboardPage() {
             icon={<CheckCircle className="h-6 w-6 text-green-400" />}
             colorClass="text-green-400"
             bgClass="bg-green-950/20"
+            tooltip={{ description: "Techniques confirmed as detectable by Blue Team with ≥2 successful tests. These attacks would be caught if a real adversary used them.", context: "Goal: maximise this number. Higher = stronger defence." }}
           />
           <CoverageSummaryCard
             title="Partial"
@@ -215,6 +218,7 @@ export default function DashboardPage() {
             icon={<AlertTriangle className="h-6 w-6 text-yellow-400" />}
             colorClass="text-yellow-400"
             bgClass="bg-yellow-950/20"
+            tooltip={{ description: "Techniques with incomplete coverage: only 1 validated test, mixed detection results, or tests still in progress.", context: "These need attention — detection is not yet reliable." }}
           />
           <CoverageSummaryCard
             title="In Progress"
@@ -223,6 +227,7 @@ export default function DashboardPage() {
             icon={<Clock className="h-6 w-6 text-blue-400" />}
             colorClass="text-blue-400"
             bgClass="bg-blue-950/20"
+            tooltip={{ description: "Techniques with active tests currently being executed or awaiting review by leads. Not yet counted as covered.", context: "Indicates active testing work underway." }}
           />
           <CoverageSummaryCard
             title="Not Covered"
@@ -231,6 +236,7 @@ export default function DashboardPage() {
             icon={<XCircle className="h-6 w-6 text-red-400" />}
             colorClass="text-red-400"
             bgClass="bg-red-950/20"
+            tooltip={{ description: "Techniques that were tested but Blue Team failed to detect the attack. These are confirmed security gaps — a real attack would go unnoticed.", context: "High priority: invest in detection rules and monitoring." }}
           />
           <CoverageSummaryCard
             title="Not Evaluated"
@@ -239,6 +245,7 @@ export default function DashboardPage() {
             icon={<HelpCircle className="h-6 w-6 text-gray-400" />}
             colorClass="text-gray-400"
             bgClass="bg-gray-900"
+            tooltip={{ description: "Techniques with no tests created yet. We have no data on whether these attacks would be detected or not.", context: "Unknown risk — prioritise testing the most common ones." }}
           />
         </div>
       )}
@@ -248,6 +255,7 @@ export default function DashboardPage() {
         <h2 className="mb-4 text-lg font-semibold text-white flex items-center gap-2">
           <TrendingUp className="h-5 w-5 text-cyan-400" />
           Coverage Evolution (6 months)
+          <MetricTooltip title="Coverage Evolution" description="How overall coverage % and organisation score have changed over the last 6 months. An upward trend means the security posture is improving." context="Org Score reflects depth of testing; Coverage % reflects breadth." />
         </h2>
         {evolutionLoading ? (
           <div className="flex h-48 items-center justify-center">
@@ -310,6 +318,7 @@ export default function DashboardPage() {
           <h2 className="text-lg font-semibold text-white flex items-center gap-2">
             <TrendingUp className="h-5 w-5 text-cyan-400" />
             Test Pipeline
+            <MetricTooltip title="Test Pipeline" description="Shows how many security tests are at each stage of the Red/Blue workflow: Draft → Red Executing → Blue Evaluating → In Review → Validated / Rejected." context="A healthy pipeline has tests flowing through to Validated. Backlogs in any stage indicate bottlenecks." />
           </h2>
           <button
             onClick={() => navigate("/tests")}
@@ -337,6 +346,7 @@ export default function DashboardPage() {
           <h2 className="mb-4 text-lg font-semibold text-white flex items-center gap-2">
             <Users className="h-5 w-5 text-cyan-400" />
             Team Activity
+            <MetricTooltip title="Team Activity" description="Shows Red Team (attackers) and Blue Team (defenders) productivity. 'Completed' = tests passed through their phase; 'Pending' = tests waiting for action." context="Low completion rate may indicate resource constraints or bottlenecks." />
           </h2>
 
           {teamLoading ? (
@@ -389,6 +399,7 @@ export default function DashboardPage() {
           <h2 className="mb-4 text-lg font-semibold text-white flex items-center gap-2">
             <CheckCircle className="h-5 w-5 text-cyan-400" />
             Validation Rate
+            <MetricTooltip title="Validation Rate" description="How many test results Red Lead and Blue Lead have reviewed and approved vs rejected. High approval = good quality tests and clear detection results." context="High rejection rate may indicate unclear test procedures or disagreement on results." />
           </h2>
 
           {validationLoading ? (
diff --git a/frontend/src/pages/ExecutiveDashboardPage.tsx b/frontend/src/pages/ExecutiveDashboardPage.tsx
index 6504eb1..3294384 100644
--- a/frontend/src/pages/ExecutiveDashboardPage.tsx
+++ b/frontend/src/pages/ExecutiveDashboardPage.tsx
@@ -23,6 +23,7 @@ import {
   Cell,
 } from "recharts";
 import { getOrganizationScore, getScoreHistory } from "../api/scores";
+import MetricTooltip from "../components/MetricTooltip";
 import {
   getOperationalMetrics,
   getMetricsByTeam,
@@ -87,11 +88,13 @@ function KPICard({
   value,
   unit,
   trend,
+  tooltip,
 }: {
   label: string;
   value: string | number;
   unit?: string;
   trend?: "improving" | "declining" | "stable" | null;
+  tooltip?: { description: string; context?: string };
 }) {
   const TrendIcon =
     trend === "improving"
@@ -109,7 +112,10 @@ function KPICard({
 
   return (
     <div className="rounded-xl border border-gray-800 bg-gray-900 p-4">
-      <p className="text-xs text-gray-500 uppercase tracking-wider">{label}</p>
+      <p className="text-xs text-gray-500 uppercase tracking-wider flex items-center gap-0.5">
+        {label}
+        {tooltip && <MetricTooltip title={label} description={tooltip.description} context={tooltip.context} />}
+      </p>
       <div className="mt-2 flex items-end justify-between">
         <div>
           <span className="text-2xl font-bold text-white">
@@ -256,33 +262,34 @@ export default function ExecutiveDashboardPage() {
               <p className="text-lg font-bold text-white">
                 {orgScore?.total_coverage ?? 0}
               </p>
-              <p className="text-[10px] text-gray-500">Coverage</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Coverage<MetricTooltip title="Coverage Score" description="Breadth of attack technique coverage — how many of the known MITRE ATT&CK techniques have been tested and detected. Scale 0–100." position="above" /></p>
             </div>
             <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
               <p className="text-lg font-bold text-white">
                 {orgScore?.detection_maturity ?? 0}
               </p>
-              <p className="text-[10px] text-gray-500">Detection</p>
+              <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Detection<MetricTooltip title="Detection Score" description="Quality and maturity of detection capabilities — based on detection rules, validated tests and Blue Team confirmation rate. Scale 0–100." position="above" /></p>
             </div>
             <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
               <p className="text-lg font-bold text-white">
                 {orgScore?.critical_coverage ?? 0}
               </p>
-              <p className="text-[10px] text-gray-500">Critical</p>
+              <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Critical<MetricTooltip title="Critical Coverage Score" description="Coverage specifically for high-risk and critical techniques used by known threat actors targeting your sector. Scale 0–100." position="above" /></p>
             </div>
             <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
               <p className="text-lg font-bold text-white">
                 {orgScore?.response_readiness ?? 0}
               </p>
-              <p className="text-[10px] text-gray-500">Response</p>
+              <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Response<MetricTooltip title="Response Readiness Score" description="How quickly and efficiently tests flow through the Red/Blue validation process. High score = fast, smooth validation workflow. Scale 0–100." position="above" /></p>
             </div>
           </div>
         </div>
 
         {/* Section 2: Trend Chart */}
         <div className="rounded-xl border border-gray-800 bg-gray-900 p-4 lg:col-span-3">
-          <h2 className="mb-3 text-sm font-semibold text-gray-300">
+          <h2 className="mb-3 text-sm font-semibold text-gray-300 flex items-center gap-1">
             Score Trend (90 days)
+            <MetricTooltip title="Score Trend" description="How the overall security posture score has evolved over the past 90 days. An upward trend indicates improving security coverage and maturity." context="Aim for a steady upward trend. Sudden drops may indicate new uncovered threats discovered." />
           </h2>
           <ResponsiveContainer width="100%" height={220}>
             <LineChart data={scoreHistory || []}>
@@ -323,8 +330,9 @@ export default function ExecutiveDashboardPage() {
 
       {/* Section 3: Top Threat Actors */}
       <div className="rounded-xl border border-gray-800 bg-gray-900 p-4">
-        <h2 className="mb-1 text-sm font-semibold text-gray-300">
+        <h2 className="mb-1 text-sm font-semibold text-gray-300 flex items-center gap-1">
           Top Threat Actors
+          <MetricTooltip title="Top Threat Actors" description="The 5 most dangerous known adversary groups ranked by how many of their attack techniques we cannot currently detect. Higher uncovered count = greater exposure to that group." context="These are real APT groups (e.g. APT28, FIN7) with documented attack playbooks. Focus testing on their techniques." />
         </h2>
         <p className="mb-3 text-[10px] text-gray-500">
           Ranked by uncovered techniques (most exposure first)
@@ -395,29 +403,34 @@ export default function ExecutiveDashboardPage() {
           label="MTTD"
           value={opMetrics?.mttd?.mean_hours ?? "N/A"}
           unit={opMetrics?.mttd ? "hrs" : undefined}
+          tooltip={{ description: "Mean Time To Detect — average hours from attack execution to Blue Team raising an alert or detecting the intrusion.", context: "Lower is better. Industry benchmark: < 24h." }}
         />
         <KPICard
           label="MTTR"
           value={opMetrics?.mttr?.mean_hours ?? "N/A"}
           unit={opMetrics?.mttr ? "hrs" : undefined}
+          tooltip={{ description: "Mean Time To Respond — average hours for a test to go from execution through the full Red/Blue validation and reach a final result.", context: "Lower is better. Reflects process efficiency and team responsiveness." }}
         />
         <KPICard
           label="Detection Efficacy"
           value={opMetrics?.detection_efficacy?.percentage ?? 0}
           unit="%"
+          tooltip={{ description: "Percentage of executed attacks that Blue Team successfully detected. 100% means every simulated attack triggered an alert.", context: "Higher is better. Below 60% indicates significant detection gaps." }}
         />
         <KPICard
           label="Validation Throughput"
           value={opMetrics?.validation_throughput?.tests_per_week ?? 0}
           unit="/week"
           trend={opMetrics?.validation_throughput?.trend}
+          tooltip={{ description: "Number of tests fully validated (approved by Red + Blue leads) per week. Shows how productive the security testing programme is.", context: "Increasing trend = programme is accelerating. Decreasing may indicate process bottlenecks." }}
         />
       </div>
 
       {/* Section 5: Coverage by Tactic */}
       <div className="rounded-xl border border-gray-800 bg-gray-900 p-4">
-        <h2 className="mb-3 text-sm font-semibold text-gray-300">
+        <h2 className="mb-3 text-sm font-semibold text-gray-300 flex items-center gap-1">
           Coverage by Tactic
+          <MetricTooltip title="Coverage by Tactic" description="How well each MITRE ATT&CK tactic (attack phase) is covered by validated tests. Tactics represent different stages of an attack, from Initial Access to Impact." context="Red bars (low coverage) are highest priority. Focus testing on those tactics first." />
         </h2>
         <ResponsiveContainer width="100%" height={300}>
           <BarChart
@@ -462,8 +475,9 @@ export default function ExecutiveDashboardPage() {
       {/* Section 6: Critical Gaps */}
       <div className="rounded-xl border border-gray-800 bg-gray-900 p-4">
         <div className="mb-3 flex items-center justify-between">
-          <h2 className="text-sm font-semibold text-gray-300">
+          <h2 className="text-sm font-semibold text-gray-300 flex items-center gap-1">
             Critical Gaps — Top 10 by Risk Priority
+            <MetricTooltip title="Critical Gaps" description="The 10 most dangerous attack techniques with no detection coverage, ranked by a composite risk score based on: how many threat actors use this technique, recent threat intelligence, and test history." context="These are your highest-priority gaps — real adversaries actively use these techniques and you cannot currently detect them." />
           </h2>
           <button
             onClick={() => computeMutation.mutate()}
@@ -581,13 +595,14 @@ export default function ExecutiveDashboardPage() {
             <h2 className="mb-3 flex items-center gap-2 text-sm font-semibold text-red-400">
               <div className="h-2 w-2 rounded-full bg-red-500" />
               Red Team
+              <MetricTooltip title="Red Team Performance" description="Metrics for the offensive security team that simulates attacks. Tests Done = completed executions; Avg Time = mean execution duration; Rejection = % of results rejected by leads." context="Lower rejection rate = higher quality test documentation." />
             </h2>
             <div className="grid grid-cols-3 gap-3">
               <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
                 <p className="text-lg font-bold text-white">
                   {teamMetrics.red_team.tests_completed}
                 </p>
-                <p className="text-[10px] text-gray-500">Tests Done</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Tests Done<MetricTooltip title="Tests Done (Red)" description="Total number of attack simulations completed by Red Team and submitted to Blue Team for evaluation." /></p>
               </div>
               <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
                 <p className="text-lg font-bold text-white">
@@ -595,13 +610,13 @@ export default function ExecutiveDashboardPage() {
                     ? `${teamMetrics.red_team.avg_completion_hours}h`
                     : "N/A"}
                 </p>
-                <p className="text-[10px] text-gray-500">Avg Time</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Avg Time<MetricTooltip title="Avg Execution Time (Red)" description="Average hours Red Team spends executing and documenting each attack simulation." /></p>
               </div>
               <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
                 <p className="text-lg font-bold text-white">
                   {teamMetrics.red_team.rejection_rate}%
                 </p>
-                <p className="text-[10px] text-gray-500">Rejection</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Rejection<MetricTooltip title="Rejection Rate (Red)" description="Percentage of Red Team submissions rejected by the Red Lead during validation review. High rejection = quality issues in test documentation." /></p>
               </div>
             </div>
           </div>
@@ -611,13 +626,14 @@ export default function ExecutiveDashboardPage() {
             <h2 className="mb-3 flex items-center gap-2 text-sm font-semibold text-blue-400">
               <div className="h-2 w-2 rounded-full bg-blue-500" />
               Blue Team
+              <MetricTooltip title="Blue Team Performance" description="Metrics for the defensive security team that analyses attacks and validates detections. Tests Done = evaluations completed; Avg Time = mean evaluation duration; Rejection = % rejected by Blue Lead." context="Lower rejection rate = consistent, high-quality detection analysis." />
             </h2>
             <div className="grid grid-cols-3 gap-3">
               <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
                 <p className="text-lg font-bold text-white">
                   {teamMetrics.blue_team.tests_completed}
                 </p>
-                <p className="text-[10px] text-gray-500">Tests Done</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Tests Done<MetricTooltip title="Tests Done (Blue)" description="Total attack simulations evaluated by Blue Team — verified whether security controls detected or missed the attack." /></p>
               </div>
               <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
                 <p className="text-lg font-bold text-white">
@@ -625,13 +641,13 @@ export default function ExecutiveDashboardPage() {
                     ? `${teamMetrics.blue_team.avg_completion_hours}h`
                     : "N/A"}
                 </p>
-                <p className="text-[10px] text-gray-500">Avg Time</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Avg Time<MetricTooltip title="Avg Evaluation Time (Blue)" description="Average hours Blue Team takes to evaluate an attack simulation and document the detection result." /></p>
               </div>
               <div className="rounded-lg bg-gray-800 px-3 py-2 text-center">
                 <p className="text-lg font-bold text-white">
                   {teamMetrics.blue_team.rejection_rate}%
                 </p>
-                <p className="text-[10px] text-gray-500">Rejection</p>
+                <p className="text-[10px] text-gray-500 flex items-center justify-center gap-0.5">Rejection<MetricTooltip title="Rejection Rate (Blue)" description="Percentage of Blue Team evaluations rejected by the Blue Lead. May indicate unclear detection documentation or disagreement on results." /></p>
               </div>
             </div>
           </div>