A pre-release version of software. Sometimes software vendors make one or two release candidates (RC1, RC2, etc.) available to select customers in advance of the official release. A release candidate is like a "sneak preview" of the final release with the added advantage that serious bugs may yet surface and be fixed before the general public uses it. Thus, there are alpha versions (internal), beta versions (external), release candidates (sometimes) and the final release of software. After that, there are countless updates that add features and fix bugs. See
alpha version and
beta version.