This is professional-level videoconferencing tech that's available for free through the current situation. It is feature-rich and yet the learning curve isn't too steep. One of the great features is that you can see all students at once in a grid on your screen. Another cool tool is the ability to put students into 'rooms' for smaller group discussions.
Update 13th April 2020
There have been many issues reported with security in Zoom. For now, if you haven't committed to any platform, it might be advisable to use Google Meet as an alternative until these issues are resolved.
Google has unlocked the premium features of this app for educators. Simple interface and handy if you are already using Google Apps. If you would like the grid view functionality of Zoom, you'll need to install a Chrome extension here.
The brilliant Eric Curts has put together a list of video and text tutorials for getting started and developing your skills with Google Meet here.