diff --git a/src/sprites/clone.js b/src/sprites/clone.js
index ce64fda52..169d72cc7 100644
--- a/src/sprites/clone.js
+++ b/src/sprites/clone.js
@@ -2,6 +2,11 @@ var util = require('util');
 var MathUtil = require('../util/math-util');
 var Target = require('../engine/target');
 
+/**
+ * Clone (instance) of a sprite. 
+ * @param {!Blocks} spriteBlocks Reference to the sprite's blocks.
+ * @constructor
+ */
 function Clone(spriteBlocks) {
     Target.call(this, spriteBlocks);
     this.drawableID = null;
diff --git a/src/sprites/sprite.js b/src/sprites/sprite.js
index 1ec25b3ba..b4abdbbb5 100644
--- a/src/sprites/sprite.js
+++ b/src/sprites/sprite.js
@@ -1,8 +1,13 @@
 var Clone = require('./clone');
 var Blocks = require('../engine/blocks');
 
+/**
+ * Sprite to be used on the Scratch stage.
+ * All clones of a sprite have shared blocks, shared costumes, shared variables.
+ * @param {?Blocks} blocks Shared blocks object for all clones of sprite.
+ * @constructor
+ */
 function Sprite (blocks) {
-    // Sprites have: shared blocks, shared costumes, shared variables, etc.
     if (!blocks) {
         // Shared set of blocks for all clones.
         blocks = new Blocks();
@@ -11,6 +16,10 @@ function Sprite (blocks) {
     this.clones = [];
 }
 
+/**
+ * Create a clone of this sprite.
+ * @returns {!Clone} Newly created clone.
+ */
 Sprite.prototype.createClone = function () {
     var newClone = new Clone(this.blocks);
     this.clones.push(newClone);