What is video chat and how it works: 

Video Chat is a video conference which allows viewing webcam video from another computer, chat and audio conversation assuming that a microphone and speakers are connected to your computer. 
Video chat enables virtual experience more powerful than the chat standards now common in the internet. The technology allows sharing video, voice and images in real time.

More use of the site YalaCam:

The YalaCam site is a free site that allows viewing a number of cameras simultaneously. A user connected to the site can select up to four camera users who allow viewing their camera, each user who is chosen to be viewed, will be shown on a  separate video screen. 
The site has various video and chat rooms that are divided into different categories. 
Each user selects the room he wanted. Members of each room will be shown, the user can choose four members of the room whose cameras will be shown on the screen. 
The YalaCam site allows group video conversation and chat with participants of the room or a private conversation with a single user by setting the user name's pane to "whisper." 
Users connected to the camera will be able to conduct a video conference call voice using a microphone. 
The YalaCam site allows sending pictures to all participants in the room during a video call or chat. 
Use of this website is simple and convenient and allows fast and quality communication without having to install software on the computer. 

What are the requirements for using the site: 

In order to correspond with participants in the video chat and to view cameras of the other users, there is no need for any installations, one can view other users' cameras even if he does not have one himself. 
A webcam, microphone and speakers will allow other users to have a video conference with you.