Choosing a Webcam:
Megapixels: Webcams, like other digital cameras, measure picture quality by the number of pixels the web camera's sensor captures in each frame of video or each still photo. One megapixel is equal to roughly a million pixels, and it's pretty common to find a webcam with more than 2 megapixels. A webcam above 3 megapixels will produce a fine picture, but beyond that you may not notice a large difference in image-quality.
HD: High megapixel counts don't necessarily translate into amazing video. Often video resolution on a webcam will be lower than its photo resolution. A true HD webcam will record video in 720p resolution or higher. For a computer monitor, this is more than high enough to produce crisp, clean video images. Higher resolution webcams can take up more system resources while recording, however.
Frame rate: Jumpy video can be distracting. More frames-per-second (fps) will create smoother movement as you video chat with friends or family online. Thirty fps or higher will produce smoother video, especially if you have a high-speed Internet connection that won't introduce lag into your conversations.
Video effects: A lot of webcams include software which may feature various picture effects, including virtual foregrounds, text, animations and other extras. These aren't essential to a web cam, but they can be fun. For more info, visit this site.