CanonWebcam is the software that allows to use Canon PowerShot series cameras as regular webcams for video conferencing, video recording, remote area monitoring, etc.

You can use any Windows software that takes standard video capture source as input. You only need to configure your video chat or other software to use CanonWebcam Capture Source and have your camera connected to USB and powered on, the rest is done automatically - search for
a connected camera and taking control over it.
Before purchasing the CanonWebcam software you can test your camera, and only when you get it working on your computer with your camera and your favorite video conferencing software you'll get ID for registering your copy online. So you try before you buy.

CanonWebcam has tray icon utility that helps you to work with camera. You have live fiewfinder there to assist pointing camera and log window to see what's going on, connection progress, events. There's Zoom track bar that you can use to get closer view, and buttons for triggering AutoFocus and Macro mode switch on and off.