Your online courses may ask you to preview audiovisual materials with programs such as Windows Media Player, Acrobat Reader, RealPlayer, VLC Media Player, and Adobe Flash. These are free and when you are enrolled in an online course, you will be given instructions on how to download the latest version of these programs, as well as how to add any others that may be required later.
Some courses, particularly those with a significant technology component, may require use of industry specific software. Software needed for these courses are generally free and mostly open source. You will receive instructions for download/install/use in class.