What is a "beta" version ?

A beta version, as opposed to a final version, is software that is undergoing its final stages in testing. We release beta versions to our customers so that the final set of bugs can be found and eliminated from WinRAR.

It is impossible to find all software bugs in a lab environment, because of the various different hardware and software setups. One person can not find all the bugs in a program. It takes many people in real-life situations, using the program for a long time, to find a bug.

We extensively test a beta version before issuing it (alpha phase).
That does not mean that the version is perfect. One or more of the changes may not work as intended. A change may be awkward, unreliable and need re-doing or a change may have an adverse effect on some other operation or function. That's why it needs testing.

WinRAR betas are numbered, this means first beta is beta 1, second beta is beta 2 and so on. Every beta version contains a "what's new" text with fixed bugs and changes.
You can find this "what's new" text at http://www.win-rar.com/whatsnew.html.

After finding and fixing a number of bugs in a beta version, we release a new beta with a new beta version number. Usually 5 - 7 beta versions are released before WinRAR gets a final version. So a beta number higher than 5 is very near to the final version.

Note, while beta testing we don't add new features to WinRAR.

After a final release, we add new features to alpha versions, which are not released outside of our software company. They are only used inside of our company for debugging and further development purposes. After adding all new features and changes to an alpha version and after extensive testing
we release the first new beta version.

This WinRAR development process can also be examined by consulting our history of versions.