RTM stands for release to manufacturer and is one of the phases the
devolopment of software goes through. Specifically, it is the phase where
the software releases to manufacturers (the final release) so they can get
drivers prepared for the software. For example, Windows Vista went to RTM
status on November 8, 2006, but manufacturers had several months to prepare
and finalize some drivers for Vista before consumers actually got it on
January 30, 2007. Normally it goes like this for the major parts:
Alpha - This is the very early pre-stages of an operating system or software
where basically everything is considered concepts at this point and rarely
things stay the same from an Alpha build to a final build. Also, Alpha
builds are typically very unstable and often slow and definitely not worth
using for every day use.
Beta - This is the next major stage of software development. This is when
ideas normally start to come together and the software might actually
represent what it will look like in the final release. Often times, beta
software is still not very stable, has a lot of bugs, and is often times not
performance optimized, so in other words, the software is still a lot slower
than it will be in the final release.
Release Candidate - This is where things actually start to get polished.
Normally, the software is performance optimized for the most part by now, so
a release candidate is typically what actually is going to represent the
final release. You could also say for *most* software that the release
candidate is the build that is intended to be used for the final release
unless bugs are found. Yes, you often times will still find lots of bugs in
a release candidate.