Guide to Platforms that can be used for sessions

Video Conferencing Systems

Video conference system work for both one and one and group sessions. They do not require you to be connected to the people you are having a session with.

Help needed!
If you know of any other video conferencing platforms that are good for online sessions, please about them

Jitsi is a free open source video conferencing system that requires no login or account connection and can handle group sessions. If it works for you it is one of the best options. If you are of a technical nature, you can self host it for added privacy. (Wikipedia Entry)
Big Blue Button is a free open source video conferencing system. If you are of a technical nature, you can self host it for added privacy. (Wikipedia Entry)
Zoom is a commercial video conferencing platform. (Wikipedia Entry)

Video Messaging Systems

There are many messaging systems that offer video chat. Unless you know the people that you are having a session with, it is generally better to use a video conferencing system for your sessions, as once the session is done, there is no lingering form of connection.

Comparison of cross-platform instant messaging clients (Wikipedia)

Help needed!
If you know of any other video messaging platforms that are good for online sessions, please about them

Here is a list of messaging systems that offer video chat. They all have different features and pros and cons!