This article explains X-Plane’s version numbering schemes, patching and beta programs.
X-Plane has a three-digit version number, sometimes written with a period (e.g. 9.01 or 901). We will use the no-period syntax for this article.
The first number is the major version scheme, e.g. X-Plane is version 10, so all releases within this major version run are 10xx.
Major upgrades are new products and must be individually purchased. The time between new releases varies; historically they’ve been about two years apart, with a few major versions running a little bit longer.
The second two digits are the minor version number, which represent upgrades, patches and bug fixes. Minor updates are free, e.g. if you buy any version of X-Plane 9, you are entitled to any future 9xx update. Minor updates are available over the web using the X-Plane Web Updater.
Typically minor versions increase by 1 for bug fix releases, and by 5 or 10 for patches that introduce new functionality. For example, after 840, the patch 850 introduced new features (a new airport file format and enhanced rendering engine). After 863, the 864 patch contained a few small bug fixes in the scenery system.
The sim may be labeled with a suffix like r3 or b5. This is for a beta or release.
At any one time there is a current version of the sim, and there may also be a newer current beta. A setting in the X-Plane Web Updater controls whether the updater will fetch a new beta or only a final release.
A build is labeled beta if it is stable enough to run but still contains known bugs. Typically a beta will have a name like 901b1 for version 9.01 beta 1.
A build is labeled as a release candidate if it has no known bugs. If the release candidate continues to appear bug free, it is declared “final” and becomes the release; otherwise we fix the bugs and release a new release candidate.
Release candidates have version numbers like 900r3 (X-Plane 900 release candidate 3). When a release candidate is declared final, it is the final version – there will be no re-release of the release candidate.
Thus if you download X-Plane 9 final you will see the version 900r3. This just means that it took us three tries to create the final build.
Release candidates are downloadable using the installer in “beta” mode until they are declared final; after that they are moved to the regular update process.
The short answer is: probably not. If you don’t already know the answer about whether you want betas, the best thing is to avoid them.
A beta is unfinished software; the purpose of the X-Plane public beta program is to allow us to find bugs that do not appear on our development computers, to test X-Plane on a very wide range of hardware, and to give third party developers and authors a chance to test compatibility and report bugs.
If you develop a third party add-on for X-Plane, you definitely should participate in the beta program; it is much easier for us to fix third-party compatibility bugs if they are reported early in beta.
If you are simply a user, you may want to avoid betas, as they sometimes crash or have serious problems. We do not release betas with known crash bugs, but often serious bugs are specific to hardware we do not have.