diff --git a/src-tauri/src/sketchbook/_sketch/_impl_session_state.rs b/src-tauri/src/sketchbook/_sketch/_impl_session_state.rs
index 978990c..de1f351 100644
--- a/src-tauri/src/sketchbook/_sketch/_impl_session_state.rs
+++ b/src-tauri/src/sketchbook/_sketch/_impl_session_state.rs
@@ -2,7 +2,7 @@ use crate::app::event::Event;
 use crate::app::state::{Consumed, SessionHelper, SessionState};
 use crate::app::DynError;
 use crate::sketchbook::data_structs::SketchData;
-use crate::sketchbook::event_utils::make_state_change;
+use crate::sketchbook::event_utils::{make_reversible, make_state_change};
 use crate::sketchbook::{JsonSerde, Sketch};
 use std::fs::File;
 use std::io::Read;
@@ -100,6 +100,21 @@ impl SessionState for Sketch {
                 state_change,
                 reset: false,
             })
+        } else if Self::starts_with("set_annotation", at_path).is_some() {
+            let new_annotation = Self::clone_payload_str(event, "sketch")?;
+            let orig_annotation = self.get_annotation().to_string();
+            if new_annotation == orig_annotation {
+                return Ok(Consumed::NoChange);
+            }
+
+            // set the annotation and prepare state-change + reverse events
+            self.set_annotation(&new_annotation);
+            let payload = serde_json::to_string(&new_annotation).unwrap();
+            let state_change = Event::build(&["sketch", "set_annotation"], Some(&payload));
+            let mut reverse_event = event.clone();
+            reverse_event.payload = Some(orig_annotation);
+
+            Ok(make_reversible(state_change, event, reverse_event))
         } else if Self::starts_with("assert_consistency", at_path).is_some() {
             // this is a "synthetic" event that either returns an error, or Consumed::NoChange
             self.assert_consistency()?;
diff --git a/src/aeon_state.ts b/src/aeon_state.ts
index 838ea43..8ee1e2a 100644
--- a/src/aeon_state.ts
+++ b/src/aeon_state.ts
@@ -177,8 +177,7 @@ interface AeonState {
 
     /** Run the explicit consistency check on the sketch. */
     checkConsistency: () => void
-    /** Results of an explicit consistency check. */
-    // TODO: make properly (now just a string)
+    /** Results of an explicit consistency check (a summary message). */
     consistencyResults: Observable<string>
     /** Export the sketch data to a file. */
     exportSketch: (path: string) => void
@@ -192,6 +191,10 @@ interface AeonState {
     newSketch: () => void
     /** The whole replaced sketch instance (after importing or starting a new sketch). */
     sketchReplaced: Observable<SketchData>
+    /** Set annotation of the whole sketch. */
+    setAnnotation: (annotation: string) => void
+    /** Annotation of the whole sketch was changed. */
+    annotationChanged: Observable<string>
 
     /** The state of the main model. */
     model: {
@@ -578,6 +581,10 @@ export const aeonState: AeonState = {
   },
   sketch: {
     sketchRefreshed: new Observable<SketchData>(['sketch', 'get_whole_sketch']),
+    consistencyResults: new Observable<string>(['sketch', 'consistency_results']),
+    sketchReplaced: new Observable<SketchData>(['sketch', 'set_all']),
+    annotationChanged: new Observable<string>(['sketch', 'set_annotation']),
+
     refreshSketch (): void {
       aeonEvents.refresh(['sketch', 'get_whole_sketch'])
     },
@@ -587,7 +594,6 @@ export const aeonState: AeonState = {
         payload: path
       })
     },
-    sketchReplaced: new Observable<SketchData>(['sketch', 'set_all']),
     importSketch (path: string): void {
       aeonEvents.emitAction({
         path: ['sketch', 'import_sketch'],
@@ -618,7 +624,12 @@ export const aeonState: AeonState = {
         payload: null
       })
     },
-    consistencyResults: new Observable<string>(['sketch', 'consistency_results']),
+    setAnnotation (annotation: string): void {
+      aeonEvents.emitAction({
+        path: ['sketch', 'set_annotation'],
+        payload: annotation
+      })
+    },
 
     model: {
       modelRefreshed: new Observable<ModelData>(['sketch', 'model', 'get_whole_model']),
diff --git a/src/html/component-editor/annotations-tab/annotations-tab.less b/src/html/component-editor/annotations-tab/annotations-tab.less
index eccba83..9fa28c1 100644
--- a/src/html/component-editor/annotations-tab/annotations-tab.less
+++ b/src/html/component-editor/annotations-tab/annotations-tab.less
@@ -48,3 +48,28 @@
 .header h3 {
   color: @text-dark;
 }
+
+.sketch-annotation {
+  width: 100%;
+  padding: 0;
+  border: none;
+  background: none;
+  resize: vertical;
+  font-size: inherit;
+  font-family: inherit;
+  color: inherit;
+  outline: none;
+}
+
+textarea::placeholder {
+  font-weight: inherit;
+  color: rgba(255, 255, 255, 0.7);
+}
+
+.sketch-annotation:focus {
+  border: 1px solid lightgray; 
+}
+
+.placeholder {
+  color: rgba(255, 255, 255, 0.7);
+}
diff --git a/src/html/component-editor/annotations-tab/annotations-tab.ts b/src/html/component-editor/annotations-tab/annotations-tab.ts
index ea1e49e..2f448fc 100644
--- a/src/html/component-editor/annotations-tab/annotations-tab.ts
+++ b/src/html/component-editor/annotations-tab/annotations-tab.ts
@@ -4,48 +4,60 @@ import style_less from './annotations-tab.less?inline'
 import { ContentData, type IObservationSet } from '../../util/data-interfaces'
 import './annotation-tile/annotation-tile'
 import './annotation-tile/dataset-tile'
+import { aeonState } from '../../../aeon_state'
 
 @customElement('annotations-tab')
 export class AnnotationsTab extends LitElement {
   static styles = css`${unsafeCSS(style_less)}`
   @property() contentData = ContentData.create()
 
-  addSketchAnnot (): void {
-    // TODO
+  constructor () {
+    super()
+    aeonState.sketch.annotationChanged.addEventListener(this.#annotationChanged.bind(this))
   }
 
-  formatSketchAnnotation (): TemplateResult<1> {
-    return html`No annotations available for the sketch.`
+  #annotationChanged (annotation: string): void {
+    // propagate the current version of annotation via event that will be captured by root component
+    this.dispatchEvent(new CustomEvent('save-annotation', {
+      bubbles: true,
+      composed: true,
+      detail: { annotation }
+    }))
   }
 
-  addVarAnnot (): void {
-    // TODO
+  private changeAnnotation (event: Event): void {
+    const target = event.target as HTMLTextAreaElement
+    aeonState.sketch.setAnnotation(target.value)
+  }
+
+  formatSketchAnnotation (): TemplateResult<1> {
+    return html`
+      <textarea
+        class="sketch-annotation"
+        .value="${this.contentData.annotation}"
+        @focusout="${this.changeAnnotation}"
+        placeholder="Click to annotate the sketch..."
+        rows="2"
+      ></textarea>
+    `
   }
 
   formatVarAnnotations (): TemplateResult<1> {
     const annotatedVars = this.contentData.variables
       .filter(variable => variable.annotation.trim() !== '')
     if (annotatedVars.length === 0) {
-      return html`<p>No annotations available for variables.</p>`
+      return html`<div class="placeholder"><p>No annotations available for variables.</p></div>`
     }
-    return html`${annotatedVars.map(variable => this.renderAnnotationTile(variable.id, variable.annotation))}`
-  }
-
-  addFnAnnot (): void {
-    // TODO
+    return html`<div>${annotatedVars.map(variable => this.renderAnnotationTile(variable.id, variable.annotation))}</div>`
   }
 
   formatFnAnnotations (): TemplateResult<1> {
     const annotatedFns = this.contentData.functions
       .filter(func => func.annotation.trim() !== '')
     if (annotatedFns.length === 0) {
-      return html`<p>No annotations available for functions.</p>`
+      return html`<div class="placeholder"><p>No annotations available for functions.</p></div>`
     }
-    return html`${annotatedFns.map(func => this.renderAnnotationTile(func.id, func.annotation))}`
-  }
-
-  addDatasetAnnot (): void {
-    // TODO
+    return html`<div>${annotatedFns.map(func => this.renderAnnotationTile(func.id, func.annotation))}</div>`
   }
 
   formatDatasetAnnotations (): TemplateResult<1> {
@@ -53,35 +65,27 @@ export class AnnotationsTab extends LitElement {
       .filter(d => d.annotation.trim() !== '' || d.observations.some(obs => obs.annotation.trim() !== ''))
 
     if (annotatedDatasets.length === 0) {
-      return html`<p>No annotations available for datasets or observations.</p>`
+      return html`<div class="placeholder"><p>No annotations available for datasets or observations.</p></div>`
     }
-    return html`${annotatedDatasets.map(dataset => this.renderDatasetTile(dataset))}`
-  }
-
-  addDynPropAnnot (): void {
-    // TODO
+    return html`<div>${annotatedDatasets.map(dataset => this.renderDatasetTile(dataset))}</div>`
   }
 
   formatDynPropAnnotations (): TemplateResult<1> {
     const annotatedProps = this.contentData.dynamicProperties
       .filter(dynProp => dynProp.annotation.trim() !== '')
     if (annotatedProps.length === 0) {
-      return html`<p>No annotations available for dynamic properties.</p>`
+      return html`<div class="placeholder"><p>No annotations available for dynamic properties.</p></div>`
     }
-    return html`${annotatedProps.map(dynProp => this.renderAnnotationTile(dynProp.id, dynProp.annotation))}`
-  }
-
-  addStatPropAnnot (): void {
-    // TODO
+    return html`<div>${annotatedProps.map(dynProp => this.renderAnnotationTile(dynProp.id, dynProp.annotation))}</div>`
   }
 
   formatStatPropAnnotations (): TemplateResult<1> {
     const annotatedProps = this.contentData.staticProperties
       .filter(dynProp => dynProp.annotation.trim() !== '')
     if (annotatedProps.length === 0) {
-      return html`<p>No annotations available for static properties.</p>`
+      return html`<div class="placeholder"><p>No annotations available for static properties.</p></div>`
     }
-    return html`${annotatedProps.map(statProp => this.renderAnnotationTile(statProp.id, statProp.annotation))}`
+    return html`<div>${annotatedProps.map(statProp => this.renderAnnotationTile(statProp.id, statProp.annotation))}</div>`
   }
 
   private renderAnnotationTile (id: string, content: string): TemplateResult<1> {
diff --git a/src/html/component-editor/root-component/root-component.ts b/src/html/component-editor/root-component/root-component.ts
index fb9ecf0..ecb8e0c 100644
--- a/src/html/component-editor/root-component/root-component.ts
+++ b/src/html/component-editor/root-component/root-component.ts
@@ -90,6 +90,7 @@ export default class RootComponent extends LitElement {
     this.addEventListener('save-observations', this.saveObservationData.bind(this))
     this.addEventListener('save-dynamic-properties', this.saveDynamicPropertyData.bind(this))
     this.addEventListener('save-static-properties', this.saveStaticPropertyData.bind(this))
+    this.addEventListener('save-annotation', this.saveAnnotationData.bind(this))
 
     // Since function ID change can affect many parts of the model (update fns, other uninterpreted fns, ...),
     // the event fetches the whole updated model data, and we make the change here in the root component.
@@ -148,6 +149,12 @@ export default class RootComponent extends LitElement {
     this.saveDynamicProperties(properties)
   }
 
+  saveAnnotationData (event: Event): void {
+    // update annotation propagated from AnnotationTab
+    const annotation: string = (event as CustomEvent).detail.annotation
+    this.saveAnnotation(annotation)
+  }
+
   private saveDynamicProperties (dynamicProperties: DynamicProperty[]): void {
     dynamicProperties.sort((a, b) => (a.id > b.id ? 1 : -1))
     this.data = this.data.copy({ dynamicProperties })
@@ -182,6 +189,10 @@ export default class RootComponent extends LitElement {
     this.data = this.data.copy({ layout })
   }
 
+  private saveAnnotation (annotation: string): void {
+    this.data = this.data.copy({ annotation })
+  }
+
   // Wrapper to save all components of the model at the same time.
   // Saving everything at the same time can help dealing with inconsistencies.
   private saveWholeModel (
@@ -205,7 +216,8 @@ export default class RootComponent extends LitElement {
     layout: ILayoutData,
     observations: IObservationSet[],
     staticProperties: StaticProperty[],
-    dynamicProperties: DynamicProperty[]
+    dynamicProperties: DynamicProperty[],
+    annotation: string
   ): void {
     functions.sort((a, b) => (a.id > b.id ? 1 : -1))
     variables.sort((a, b) => (a.id > b.id ? 1 : -1))
@@ -213,7 +225,16 @@ export default class RootComponent extends LitElement {
     staticProperties.sort((a, b) => (a.id > b.id ? 1 : -1))
     dynamicProperties.sort((a, b) => (a.id > b.id ? 1 : -1))
     observations.sort((a, b) => (a.id > b.id ? 1 : -1))
-    this.data = this.data.copy({ functions, variables, regulations, layout, staticProperties, dynamicProperties, observations })
+    this.data = this.data.copy({
+      functions,
+      variables,
+      regulations,
+      layout,
+      staticProperties,
+      dynamicProperties,
+      observations,
+      annotation
+    })
   }
 
   // Set variable data (currently, sets a name and annotation).
@@ -410,7 +431,16 @@ export default class RootComponent extends LitElement {
     const regulations = sketch.model.regulations.map(r => convertToIRegulation(r))
     const layout = convertToILayout(sketch.model.layouts[0].nodes)
 
-    this.saveWholeSketch(functions, variables, regulations, layout, datasets, sketch.stat_properties, sketch.dyn_properties)
+    this.saveWholeSketch(
+      functions,
+      variables,
+      regulations,
+      layout,
+      datasets,
+      sketch.stat_properties,
+      sketch.dyn_properties,
+      sketch.annotation
+    )
   }
 
   // refresh all components of the model, and save them at the same time
diff --git a/src/html/util/data-interfaces.ts b/src/html/util/data-interfaces.ts
index 3776bb1..d011a75 100644
--- a/src/html/util/data-interfaces.ts
+++ b/src/html/util/data-interfaces.ts
@@ -45,6 +45,7 @@ export class ContentData extends Data {
   observations: IObservationSet[] = []
   dynamicProperties: DynamicProperty[] = []
   staticProperties: StaticProperty[] = []
+  annotation: string = ''
 }
 
 export interface IFunctionData {