making them the lowest-cost form of videotelephony.
For example, the position of a single light source can be tracked and used to emulate a mouse pointer, a head-mounted light would enable hands-free computing and would greatly improve computer accessibility.
The lenses of the cameras are removed and then these are attached to telescopes to record images, video, still, or both.
In newer techniques, videos of very faint objects are taken for a couple of seconds and then all the frames of the video are "stacked" together to obtain a still image of respectable contrast.
Webcam features and performance can vary by program, computer operating system, and also by the computer's processor capabilities.
Video calling support has also been added to several popular instant messaging programs. Software is available to allow PC-connected cameras to watch for movement and sound, a computer e-mailed images of the burglar during the theft of the computer, enabling the owner to give police a clear picture of the burglar's face even after the computer had been stolen.
For a more complete list see Comparison of webcam software.
Special software can use the video stream from a webcam to assist or enhance a user's control of applications and games.
By removing the IR filter of the webcam, IR LEDs can be used, which has the advantage of being invisible to the naked eye, removing a distraction from the user.
Track IR is a commercial version of this technology.
Unauthorized access of webcams can present significant privacy issues (see "Privacy" section below).
In December 2011, Russia announced that 290,000 Webcams would be installed in 90,000 polling stations to monitor the Russian presidential election, 2012.