Some webcast applications have the functionality to replace the background of the location where you are sitting. This is a helpful way to ensure that you look professional and avoid distraction coming from whatever is happening behind you. You may not want people to see your interior, expensive stuff that you own.
Having a virtual background can be set-up in certain webcast applications, however the quality may vary.
Especially when making certain movements or with certain light conditions part of your body or face may disappear.
To avoid this from happening you can opt to put a green screen behind you.
This could significantly improve the quality of the software to replace the background with another picture or video.