A short guide below on how to join any of these meetings if you receive an invite. In order to join a Skype meeting, you must have a Skype account and the app installed either on your desktop or your phone (although Skype did have a web interface which may work from a browser). The person inviting you to the meeting will need your Skype ID or your email associated with the ID.
A Jitsi invite I know from experience requires no registration or installation even for the person hosting - can't be more seamless than that!
A lot of daily activity is moving online with countries going into full or partial lockdowns because of COVID-19. To that end, lots of people are learning %