Statalist is the place to go with questions about how to do things in any version of Stata. It is very active: Stata developers from StataCorp and many experienced users are leading members. Questions cover basic Stata use, Stata programming, and statistical practice. Before posting do study the FAQ Advice here. People are asked to use their real names. As a resource with very many answered questions and for its collective expertise, Statalist is ahead of all other forums.
Questions about Stata syntax, programming and output are addressed on StackOverflow. It's best to note its aim of being a forum for professional and enthusiast programmers and its focus on specific problems with people's own code. That is, SO is not a good forum for questions that are entirely or mostly statistical, including why or how Stata commands work.
Reddit occasionally includes Stata questions. Beginner questions are common. The number of experienced users lurking there is far smaller than on Statalist and advice is variable. There is more tolerance there for students seeking advice or assistance with their assignments, a plus or minus depending on your status and your question.
Much the same applies to Talk Stats, which appears to have faded away as a forum for Stata questions. EDIT 12 May 2023 This site now appears defunct.
Both of these last two sites allow anonymous identifiers, a plus if that is your preference.
Stata Forum.De is dedicated to Stata and is conducted in German. There is now little traffic.
Quora supports posting of opinions about Stata and its alternatives. Specific threads based on coding seem rare at best.
There is a Stata Users Group on Facebook. It supports questions in Spanish as well as in English.
Stata is often mentioned on Twitter but only a few posts ask for or provide support on specific questions.
The official FAQs are extremely useful as well. The help files for specific commands are available online; for direct access, form the url as
http://www.stata.com/help.cgi? appended with the command name, like
regress: http://www.stata.com/help.cgi?regress. The full pdf documentation is also available online, e.g., the User Guide and the Reference manuals are usually a good place to start for general commands.
StataCorp also maintains a YouTube training channel and offers registered users free technical support via e-mail.
ATS/UCLA has an entire section dedicated to Stata. Start from there with the learning modules, the FAQs or the "links by topic."
The StataCorp website carries information on, and a way to purchase, books on Stata: see this page.