What is beta and alpha software?

Occasionally you will run into software with an 'a', 'b', or the Greek letters alpha or beta in their version number.

These are developer test applications. As such most developers distribute them either with a nondisclosure agreement, or as an open software, an open place to discuss improvements before full public release.

Before getting such software read any license agreements carefully and backup your data twice.

https://discussions.apple.com/docs/DOC-1992

The ideal backup is a clone, which can boot the system and restore to exactly where it was before installing the said software. Furthermore there are some situations where if you update your operating system while the clone is attached to the computer, it becomes unreadable. Once your clones are tested, remove them from the machine after the machine is shut down, and before installing software to avoid this issue.

Verify with the developer how the release version will be installed? Will it allow itself to overwrite the test version, or will you have to remove all traces of the test version to maintain a stable system?

These are questions you should ask before becoming a subject to anyone's test software.