How To: Create layer masks in Adobe Flash

Layer masks create a viewing window to the layer(s) behind it. Manipulating the mask can create certain effects or animation without editing the object or layer directly.
Whether you're new to Adobe's popular Flash-development platform or a seasoned web developer looking to better acquaint yourself with Flash CS3, you're sure to benefit from this free software tutorial. For more information, including detailed, step-by-step instructions, watch this video guide.