diff --git a/src/vs/base/common/strings.ts b/src/vs/base/common/strings.ts
index c629bfb92c07b..8b1cdf176b56b 100644
--- a/src/vs/base/common/strings.ts
+++ b/src/vs/base/common/strings.ts
@@ -48,6 +48,19 @@ export function format2(template: string, values: Record<string, unknown>): stri
 	return template.replace(_format2Regexp, (match, group) => (values[group] ?? match) as string);
 }
 
+export function htmlAttributeEncodeValue(value: string): string {
+	return value.replace(/[<>"'&]/g, ch => {
+		switch (ch) {
+			case '<': return '&lt;';
+			case '>': return '&gt;';
+			case '"': return '&quot;';
+			case '\'': return '&apos;';
+			case '&': return '&amp;';
+		}
+		return ch;
+	});
+}
+
 /**
  * Converts HTML characters inside the string to use entities instead. Makes the string safe from
  * being used e.g. in HTMLElement.innerHTML.
diff --git a/src/vs/editor/browser/viewParts/glyphMargin/glyphMargin.ts b/src/vs/editor/browser/viewParts/glyphMargin/glyphMargin.ts
index 7323615254139..ff4739bb506b1 100644
--- a/src/vs/editor/browser/viewParts/glyphMargin/glyphMargin.ts
+++ b/src/vs/editor/browser/viewParts/glyphMargin/glyphMargin.ts
@@ -20,17 +20,17 @@ import { ViewContext } from 'vs/editor/common/viewModel/viewContext';
  * This can end up producing multiple `LineDecorationToRender`.
  */
 export class DecorationToRender {
-	_decorationToRenderBrand: void = undefined;
+	public readonly _decorationToRenderBrand: void = undefined;
 
-	public startLineNumber: number;
-	public endLineNumber: number;
-	public className: string;
 	public readonly zIndex: number;
 
-	constructor(startLineNumber: number, endLineNumber: number, className: string, zIndex: number | undefined) {
-		this.startLineNumber = +startLineNumber;
-		this.endLineNumber = +endLineNumber;
-		this.className = String(className);
+	constructor(
+		public readonly startLineNumber: number,
+		public readonly endLineNumber: number,
+		public readonly className: string,
+		public readonly tooltip: string | null,
+		zIndex: number | undefined,
+	) {
 		this.zIndex = zIndex ?? 0;
 	}
 }
@@ -42,6 +42,7 @@ export class LineDecorationToRender {
 	constructor(
 		public readonly className: string,
 		public readonly zIndex: number,
+		public readonly tooltip: string | null,
 	) { }
 }
 
@@ -108,7 +109,7 @@ export abstract class DedupOverlay extends DynamicViewOverlay {
 			}
 
 			for (let i = startLineIndex; i <= prevEndLineIndex; i++) {
-				output[i].add(new LineDecorationToRender(className, zIndex));
+				output[i].add(new LineDecorationToRender(className, zIndex, d.tooltip));
 			}
 		}
 
diff --git a/src/vs/editor/browser/viewParts/linesDecorations/linesDecorations.ts b/src/vs/editor/browser/viewParts/linesDecorations/linesDecorations.ts
index 95d8caaed5123..9bbfeffae5764 100644
--- a/src/vs/editor/browser/viewParts/linesDecorations/linesDecorations.ts
+++ b/src/vs/editor/browser/viewParts/linesDecorations/linesDecorations.ts
@@ -78,11 +78,11 @@ export class LinesDecorationsOverlay extends DedupOverlay {
 			const linesDecorationsClassName = d.options.linesDecorationsClassName;
 			const zIndex = d.options.zIndex;
 			if (linesDecorationsClassName) {
-				r[rLen++] = new DecorationToRender(d.range.startLineNumber, d.range.endLineNumber, linesDecorationsClassName, zIndex);
+				r[rLen++] = new DecorationToRender(d.range.startLineNumber, d.range.endLineNumber, linesDecorationsClassName, d.options.linesDecorationsTooltip ?? null, zIndex);
 			}
 			const firstLineDecorationClassName = d.options.firstLineDecorationClassName;
 			if (firstLineDecorationClassName) {
-				r[rLen++] = new DecorationToRender(d.range.startLineNumber, d.range.startLineNumber, firstLineDecorationClassName, zIndex);
+				r[rLen++] = new DecorationToRender(d.range.startLineNumber, d.range.startLineNumber, firstLineDecorationClassName, d.options.linesDecorationsTooltip ?? null, zIndex);
 			}
 		}
 		return r;
@@ -103,7 +103,12 @@ export class LinesDecorationsOverlay extends DedupOverlay {
 			const decorations = toRender[lineIndex].getDecorations();
 			let lineOutput = '';
 			for (const decoration of decorations) {
-				lineOutput += '<div class="cldr ' + decoration.className + common;
+				let addition = '<div class="cldr ' + decoration.className;
+				if (decoration.tooltip !== null) {
+					addition += '" title="' + decoration.tooltip; // The tooltip is already escaped.
+				}
+				addition += common;
+				lineOutput += addition;
 			}
 			output[lineIndex] = lineOutput;
 		}
diff --git a/src/vs/editor/browser/viewParts/marginDecorations/marginDecorations.ts b/src/vs/editor/browser/viewParts/marginDecorations/marginDecorations.ts
index 23101cc29eca2..f8f879cb50e39 100644
--- a/src/vs/editor/browser/viewParts/marginDecorations/marginDecorations.ts
+++ b/src/vs/editor/browser/viewParts/marginDecorations/marginDecorations.ts
@@ -64,7 +64,7 @@ export class MarginViewLineDecorationsOverlay extends DedupOverlay {
 			const marginClassName = d.options.marginClassName;
 			const zIndex = d.options.zIndex;
 			if (marginClassName) {
-				r[rLen++] = new DecorationToRender(d.range.startLineNumber, d.range.endLineNumber, marginClassName, zIndex);
+				r[rLen++] = new DecorationToRender(d.range.startLineNumber, d.range.endLineNumber, marginClassName, null, zIndex);
 			}
 		}
 		return r;
diff --git a/src/vs/editor/common/model.ts b/src/vs/editor/common/model.ts
index b5cfb6cf6c7c6..7677c2b5002b4 100644
--- a/src/vs/editor/common/model.ts
+++ b/src/vs/editor/common/model.ts
@@ -169,6 +169,10 @@ export interface IModelDecorationOptions {
 	 * If set, the decoration will be rendered in the lines decorations with this CSS class name.
 	 */
 	linesDecorationsClassName?: string | null;
+	/**
+	 * Controls the tooltip text of the line decoration.
+	 */
+	linesDecorationsTooltip?: string | null;
 	/**
 	 * If set, the decoration will be rendered in the lines decorations with this CSS class name, but only for the first line in case of line wrapping.
 	 */
diff --git a/src/vs/editor/common/model/textModel.ts b/src/vs/editor/common/model/textModel.ts
index ea5f3ffea5e6e..ab1ca0cda2123 100644
--- a/src/vs/editor/common/model/textModel.ts
+++ b/src/vs/editor/common/model/textModel.ts
@@ -2297,6 +2297,7 @@ export class ModelDecorationOptions implements model.IModelDecorationOptions {
 	readonly glyphMargin?: model.IModelDecorationGlyphMarginOptions | null | undefined;
 	readonly glyphMarginClassName: string | null;
 	readonly linesDecorationsClassName: string | null;
+	readonly linesDecorationsTooltip: string | null;
 	readonly firstLineDecorationClassName: string | null;
 	readonly marginClassName: string | null;
 	readonly inlineClassName: string | null;
@@ -2328,6 +2329,7 @@ export class ModelDecorationOptions implements model.IModelDecorationOptions {
 		this.glyphMargin = options.glyphMarginClassName ? new ModelDecorationGlyphMarginOptions(options.glyphMargin) : null;
 		this.glyphMarginClassName = options.glyphMarginClassName ? cleanClassName(options.glyphMarginClassName) : null;
 		this.linesDecorationsClassName = options.linesDecorationsClassName ? cleanClassName(options.linesDecorationsClassName) : null;
+		this.linesDecorationsTooltip = options.linesDecorationsTooltip ? strings.htmlAttributeEncodeValue(options.linesDecorationsTooltip) : null;
 		this.firstLineDecorationClassName = options.firstLineDecorationClassName ? cleanClassName(options.firstLineDecorationClassName) : null;
 		this.marginClassName = options.marginClassName ? cleanClassName(options.marginClassName) : null;
 		this.inlineClassName = options.inlineClassName ? cleanClassName(options.inlineClassName) : null;
diff --git a/src/vs/editor/contrib/folding/browser/foldingDecorations.ts b/src/vs/editor/contrib/folding/browser/foldingDecorations.ts
index 068afcbf6425d..03a9b4a402c26 100644
--- a/src/vs/editor/contrib/folding/browser/foldingDecorations.ts
+++ b/src/vs/editor/contrib/folding/browser/foldingDecorations.ts
@@ -24,6 +24,9 @@ export const foldingManualExpandedIcon = registerIcon('folding-manual-expanded',
 
 const foldedBackgroundMinimap = { color: themeColorFromId(foldBackground), position: MinimapPosition.Inline };
 
+const collapsed = localize('linesCollapsed', "Click to expand the range.");
+const expanded = localize('linesExpanded', "Click to collapse the range.");
+
 export class FoldingDecorationProvider implements IDecorationProvider {
 
 	private static readonly COLLAPSED_VISUAL_DECORATION = ModelDecorationOptions.register({
@@ -31,6 +34,7 @@ export class FoldingDecorationProvider implements IDecorationProvider {
 		stickiness: TrackedRangeStickiness.AlwaysGrowsWhenTypingAtEdges,
 		afterContentClassName: 'inline-folded',
 		isWholeLine: true,
+		linesDecorationsTooltip: collapsed,
 		firstLineDecorationClassName: ThemeIcon.asClassName(foldingCollapsedIcon),
 	});
 
@@ -41,6 +45,7 @@ export class FoldingDecorationProvider implements IDecorationProvider {
 		className: 'folded-background',
 		minimap: foldedBackgroundMinimap,
 		isWholeLine: true,
+		linesDecorationsTooltip: collapsed,
 		firstLineDecorationClassName: ThemeIcon.asClassName(foldingCollapsedIcon)
 	});
 
@@ -49,6 +54,7 @@ export class FoldingDecorationProvider implements IDecorationProvider {
 		stickiness: TrackedRangeStickiness.AlwaysGrowsWhenTypingAtEdges,
 		afterContentClassName: 'inline-folded',
 		isWholeLine: true,
+		linesDecorationsTooltip: collapsed,
 		firstLineDecorationClassName: ThemeIcon.asClassName(foldingManualCollapsedIcon)
 	});
 
@@ -59,6 +65,7 @@ export class FoldingDecorationProvider implements IDecorationProvider {
 		className: 'folded-background',
 		minimap: foldedBackgroundMinimap,
 		isWholeLine: true,
+		linesDecorationsTooltip: collapsed,
 		firstLineDecorationClassName: ThemeIcon.asClassName(foldingManualCollapsedIcon)
 	});
 
@@ -66,7 +73,8 @@ export class FoldingDecorationProvider implements IDecorationProvider {
 		description: 'folding-no-controls-range-decoration',
 		stickiness: TrackedRangeStickiness.AlwaysGrowsWhenTypingAtEdges,
 		afterContentClassName: 'inline-folded',
-		isWholeLine: true
+		isWholeLine: true,
+		linesDecorationsTooltip: collapsed,
 	});
 
 	private static readonly NO_CONTROLS_COLLAPSED_HIGHLIGHTED_RANGE_DECORATION = ModelDecorationOptions.register({
@@ -75,35 +83,40 @@ export class FoldingDecorationProvider implements IDecorationProvider {
 		afterContentClassName: 'inline-folded',
 		className: 'folded-background',
 		minimap: foldedBackgroundMinimap,
-		isWholeLine: true
+		isWholeLine: true,
+		linesDecorationsTooltip: collapsed,
 	});
 
 	private static readonly EXPANDED_VISUAL_DECORATION = ModelDecorationOptions.register({
 		description: 'folding-expanded-visual-decoration',
 		stickiness: TrackedRangeStickiness.NeverGrowsWhenTypingAtEdges,
 		isWholeLine: true,
-		firstLineDecorationClassName: 'alwaysShowFoldIcons ' + ThemeIcon.asClassName(foldingExpandedIcon)
+		firstLineDecorationClassName: 'alwaysShowFoldIcons ' + ThemeIcon.asClassName(foldingExpandedIcon),
+		linesDecorationsTooltip: expanded,
 	});
 
 	private static readonly EXPANDED_AUTO_HIDE_VISUAL_DECORATION = ModelDecorationOptions.register({
 		description: 'folding-expanded-auto-hide-visual-decoration',
 		stickiness: TrackedRangeStickiness.NeverGrowsWhenTypingAtEdges,
 		isWholeLine: true,
-		firstLineDecorationClassName: ThemeIcon.asClassName(foldingExpandedIcon)
+		firstLineDecorationClassName: ThemeIcon.asClassName(foldingExpandedIcon),
+		linesDecorationsTooltip: expanded,
 	});
 
 	private static readonly MANUALLY_EXPANDED_VISUAL_DECORATION = ModelDecorationOptions.register({
 		description: 'folding-manually-expanded-visual-decoration',
 		stickiness: TrackedRangeStickiness.AlwaysGrowsWhenTypingAtEdges,
 		isWholeLine: true,
-		firstLineDecorationClassName: 'alwaysShowFoldIcons ' + ThemeIcon.asClassName(foldingManualExpandedIcon)
+		firstLineDecorationClassName: 'alwaysShowFoldIcons ' + ThemeIcon.asClassName(foldingManualExpandedIcon),
+		linesDecorationsTooltip: expanded,
 	});
 
 	private static readonly MANUALLY_EXPANDED_AUTO_HIDE_VISUAL_DECORATION = ModelDecorationOptions.register({
 		description: 'folding-manually-expanded-auto-hide-visual-decoration',
 		stickiness: TrackedRangeStickiness.AlwaysGrowsWhenTypingAtEdges,
 		isWholeLine: true,
-		firstLineDecorationClassName: ThemeIcon.asClassName(foldingManualExpandedIcon)
+		firstLineDecorationClassName: ThemeIcon.asClassName(foldingManualExpandedIcon),
+		linesDecorationsTooltip: expanded,
 	});
 
 	private static readonly NO_CONTROLS_EXPANDED_RANGE_DECORATION = ModelDecorationOptions.register({
diff --git a/src/vs/monaco.d.ts b/src/vs/monaco.d.ts
index eb224d668bfc2..475fe169dbf7a 100644
--- a/src/vs/monaco.d.ts
+++ b/src/vs/monaco.d.ts
@@ -1699,6 +1699,10 @@ declare namespace monaco.editor {
 		 * If set, the decoration will be rendered in the lines decorations with this CSS class name.
 		 */
 		linesDecorationsClassName?: string | null;
+		/**
+		 * Controls the tooltip text of the line decoration.
+		 */
+		linesDecorationsTooltip?: string | null;
 		/**
 		 * If set, the decoration will be rendered in the lines decorations with this CSS class name, but only for the first line in case of line wrapping.
 		 */
diff --git a/src/vs/workbench/contrib/scm/browser/dirtydiffDecorator.ts b/src/vs/workbench/contrib/scm/browser/dirtydiffDecorator.ts
index d8cb0d68bf61f..e99121e3d6d51 100644
--- a/src/vs/workbench/contrib/scm/browser/dirtydiffDecorator.ts
+++ b/src/vs/workbench/contrib/scm/browser/dirtydiffDecorator.ts
@@ -1047,7 +1047,7 @@ const overviewRulerDeletedForeground = registerColor('editorOverviewRuler.delete
 
 class DirtyDiffDecorator extends Disposable {
 
-	static createDecoration(className: string, options: { gutter: boolean; overview: { active: boolean; color: string }; minimap: { active: boolean; color: string }; isWholeLine: boolean }): ModelDecorationOptions {
+	static createDecoration(className: string, tooltip: string | null, options: { gutter: boolean; overview: { active: boolean; color: string }; minimap: { active: boolean; color: string }; isWholeLine: boolean }): ModelDecorationOptions {
 		const decorationOptions: IModelDecorationOptions = {
 			description: 'dirty-diff-decoration',
 			isWholeLine: options.isWholeLine,
@@ -1055,6 +1055,7 @@ class DirtyDiffDecorator extends Disposable {
 
 		if (options.gutter) {
 			decorationOptions.linesDecorationsClassName = `dirty-diff-glyph ${className}`;
+			decorationOptions.linesDecorationsTooltip = tooltip;
 		}
 
 		if (options.overview.active) {
@@ -1096,31 +1097,33 @@ class DirtyDiffDecorator extends Disposable {
 		const overview = decorations === 'all' || decorations === 'overview';
 		const minimap = decorations === 'all' || decorations === 'minimap';
 
-		this.addedOptions = DirtyDiffDecorator.createDecoration('dirty-diff-added', {
+		const diffAdded = nls.localize('diffAdded', 'Added lines');
+		this.addedOptions = DirtyDiffDecorator.createDecoration('dirty-diff-added', diffAdded, {
 			gutter,
 			overview: { active: overview, color: overviewRulerAddedForeground },
 			minimap: { active: minimap, color: minimapGutterAddedBackground },
 			isWholeLine: true
 		});
-		this.addedPatternOptions = DirtyDiffDecorator.createDecoration('dirty-diff-added-pattern', {
+		this.addedPatternOptions = DirtyDiffDecorator.createDecoration('dirty-diff-added-pattern', diffAdded, {
 			gutter,
 			overview: { active: overview, color: overviewRulerAddedForeground },
 			minimap: { active: minimap, color: minimapGutterAddedBackground },
 			isWholeLine: true
 		});
-		this.modifiedOptions = DirtyDiffDecorator.createDecoration('dirty-diff-modified', {
+		const diffModified = nls.localize('diffModified', 'Changed lines');
+		this.modifiedOptions = DirtyDiffDecorator.createDecoration('dirty-diff-modified', diffModified, {
 			gutter,
 			overview: { active: overview, color: overviewRulerModifiedForeground },
 			minimap: { active: minimap, color: minimapGutterModifiedBackground },
 			isWholeLine: true
 		});
-		this.modifiedPatternOptions = DirtyDiffDecorator.createDecoration('dirty-diff-modified-pattern', {
+		this.modifiedPatternOptions = DirtyDiffDecorator.createDecoration('dirty-diff-modified-pattern', diffModified, {
 			gutter,
 			overview: { active: overview, color: overviewRulerModifiedForeground },
 			minimap: { active: minimap, color: minimapGutterModifiedBackground },
 			isWholeLine: true
 		});
-		this.deletedOptions = DirtyDiffDecorator.createDecoration('dirty-diff-deleted', {
+		this.deletedOptions = DirtyDiffDecorator.createDecoration('dirty-diff-deleted', nls.localize('diffDeleted', 'Removed lines'), {
 			gutter,
 			overview: { active: overview, color: overviewRulerDeletedForeground },
 			minimap: { active: minimap, color: minimapGutterDeletedBackground },