Webcams allow you to video conference over the internet, using Skype, Google Chat, AIM and other instant messaging protocols. Every laptop made since 2010 has a webcam built in, and it's now a standard feature. While a webcam over your laptop's screen is convenient and handy, not all webcams are made equal, and there are situations where a dedicated external webcam has an advantage.
1Resolution and Bandwidth: Webcams send video over the Internet using a video compression algorithm. The more pixels in the webcam's sensor, the more bandwidth-hungry your video conferences will be. The "default" webcam is 0.3 megapixels, sending VGA images at 640x480 pixels. With video compression, 30 frames per second of this type of video stream requires a broadband connection that's at least about 100 kilobits per second uploading and downloading. When the video camera collects 1.3 megapixels, it needs four times the bandwidth. The average American's home broadband connection can't quite handle the upstream requirement without getting choppy.
2Specifications: A quick perusal of laptop models as of October 2012 finds most integrated webcams at 0.3 megapixels, with a growing contingent at 1.3 megapixels, mostly on the higher end. On high-end laptops, there are 2- and 3-megapixel webcams, but due to bandwidth constraints, they may not be significantly better. A hardware limitation worth checking out is the size of the sensor on the laptop's bezel. Most are 1/3 inch or smaller. While small sensors such as this may look sleeker, they don't handle low-light conditions nearly as well as larger ones.
3The Importance of Lighting: The benefit of integrated webcams is convenience. They go anywhere your laptop goes. The drawback is ambient light. A typical flash for a still photograph puts out 2000 watts of light; most people using a webcam are using with a 100 to 150 watt bulb – anywhere from 1/20th to 1/12th the light. This degrades performance considerably, and with webcam optics confined to small spaces, bad lighting's impact gets magnified greatly in video conferencing.
4Dedicated Webcams: Some tasks aren't suitable for integrated webcams. Dedicated external webcams have a few advantages, and may be a better tool for certain tasks. They have better optics, and larger optics, which makes them work better in low light. They can be moved independently of the computer screen, which allows them to be set on more flattering camera angles. If you're recording video for later editing, a dedicated webcam is a superior tool. In order to get the most out of them in a home environment, you should also back them up with a very high-speed connection, such as a fiber-optic line.