Microsoft Teams is a Universal communication and collaboration platform that combines persistent workplace chat, video meetings, file storage (including collaboration of files), and application integration.
Zoom is a cloud-based video communications app that allows you to set up virtual video and audio conferencing, webinars, live chats, screen-sharing, and other collaborative capabilities. You don't need an account to attend a Zoom meeting.
Blackboard is a course management system used by USI faculty and students. Many of your courses will require you to use Blackboard. Students can access course materials their professors make available and participate in class discussions online.