Bitcoin Talk, originally called the Bitcoin Forum, is a message board where people interested in the technical details and the development of Bitcoin software can talk to each other. The forum also has places for people who are interested in bitcoin mining, in trading with bitcoin, and in the economics of Bitcoin.
Before the creation of the current Bitcoin Forum, Satoshi used a SourceForge forum. When Sirius provided hosting, the forum was moved to bitcoin.org/smf. Satoshi made several custom modifications to the forum software and theme.
Satoshi's first non-test post on the forum was:
I left the admin account set to the original SMF theme so if I somehow completely wedge the custom theme I can still get in to fix it.
I've got a neat little 12x12 coin image to replace those pip stars with. Should look nice. Also some nice button images to try.
The registration page has "hide your e-mail address" unchecked by default. I must fix that in php before we can open up.
The Announcements forum is currently moderator access only.
The forum was at some point moved to forum.bitcoin.org. The bitcoin.org domain name was also transferred from Satoshi to Sirius.
In July, 2011 the forum was moved to bitcointalk.org in order to make it explicitly unofficial. The "forum" link on the bitcoin.org homepage was made to simply return the Google search results for the search terms "bitcoin forums". This was followed by Bitcoin Community members, very much in bitcoin's spirit of decentralisation, creating a number of alternative forums offering different moderatorial policies and using different software platforms. None of these alternative forums have yet reached the size of Bitcoin Talk.
Later, the "forum" link was simply removed, further distancing Bitcoin Talk from the official bitcoin.org. As of April 21, 2012, Bitcoin Talk remains the first search result on Google thanks to its high page rank.
On July 22, 2012, Bitcoin Talk reached its one millionth post.