diff --git a/comment-sample/src/extension.ts b/comment-sample/src/extension.ts
index 1fb226a5..4bb53c88 100644
--- a/comment-sample/src/extension.ts
+++ b/comment-sample/src/extension.ts
@@ -6,22 +6,32 @@ let threadId = 0;
 let commentId = 0;
 
 export function activate(context: vscode.ExtensionContext) {
+	// A `CommentController` is able to provide comments for documents.
 	const commentController = vscode.comment.createCommentController('comment-sample', 'Comment API Sample');
 	context.subscriptions.push(commentController);
 
+	// commenting range provider
 	const provideCommentingRange = (document: vscode.TextDocument, token: vscode.CancellationToken) => {
 		let lineCount = document.lineCount;
 		return [new vscode.Range(0, 0, lineCount - 1, 0)];
 	};
 
+	// callback when users click `+` button on Gutter or run Create Comment command from Command Palette
 	const newCommentWidgetCallback = (document: vscode.TextDocument, range: vscode.Range) => {
+		// create a empty thread
 		let thread = commentController.createCommentThread(`${++threadId}`, document.uri, range);
+		// by default, a comment thread is collapsed, for newly created empty comment thread, we want to expand it and users can start commenting immediately
 		thread.collapsibleState = vscode.CommentThreadCollapsibleState.Expanded;
+
+		// In this example, we call it `Create New Note` while for GH PR case, we can call it `Start Review` or `Start New Converstation`
 		thread.label = 'Create New Note';
+
+		// We will render all `acceptInputCommands` as Actions on the bottom of Comment Widget in the editor.
 		thread.acceptInputCommands = [
 			{
 				title: 'Create Note',
 				command: 'mywiki.createNote',
+				// Command is responsible for arguments
 				arguments: [
 					commentController,
 					thread
@@ -30,16 +40,21 @@ export function activate(context: vscode.ExtensionContext) {
 		];
 	};
 
+	// Register commenting range provider and callback.
 	commentController.registerCommentingRangeProvider(provideCommentingRange, newCommentWidgetCallback);
 
+	// register `mywiki.createNote` command
 	context.subscriptions.push(vscode.commands.registerCommand('mywiki.createNote', (commentController: vscode.CommentController, thread: vscode.CommentThread) => {
 		if (commentController.inputBox) {
+			// Read text from the focused textarea in the Comment Widget.
 			let text = commentController.inputBox.value;
 			let markedString = new vscode.MarkdownString(text);
 			let newComment: vscode.Comment = { commentId: `${++commentId}`, body: markedString, userName: 'vscode' };
 
 			thread.comments = [newComment];
 			thread.label = 'Participants: vscode';
+
+			// After we create the new comment thread, we may want to update the actions on the Comment Widget.
 			thread.acceptInputCommands = [
 				{
 					title: 'Create Comment',
@@ -51,6 +66,7 @@ export function activate(context: vscode.ExtensionContext) {
 				}
 			];
 
+			// Lastly, we want to clear the textarea in Comment Widget.
 			commentController.inputBox.value = '';
 		}
 	}));