A conventional forum/message-board system, this contact channel is preferred by some people. In general it is used by fewer people than the mailing lists, however some local communities and languages (such as Russian) favour it more strongly.
You can log in to the forum with your main OSM account username and password (main OSM login. If you don't already have this, see Creating an Account. This is not the same as your OSM wiki login. You never need to create an account directly at the forum site)
The forum administration is: User:Lambertus.
Moderators are currently:
Hosting is generously sponsored by Oxilion.
In April 2007 the current administrator (Lambertus) took over the unofficial forum from Dave Leverton. Dave set it up as a test and never intended to run the forum for real, but users found the forum through search engines and started to use it. Due to lots of trouble with spam Dave wanted to shut the forum down. At this point Lambertus took over the forum and began running it over at osm.na1400.info until it moved to the http://forum.openstreetmap.org domain (end of October 2007).
The forum used to run PunBB because of it's low resource requirement and speed. During the conversion to a proper international forum with UTF-8 support (see below) the forum switched to FluxBB which is the opensource non-commercial alternative for PunBB.
In November 2007 the forum started using the main OpenStreetMap userbase for authentication. Since then there was no need for a separate forum username/password anymore.
OpenStreetMap is very much an international project with users speaking and writing in many languages. Unfortunately this aspect was not properly addressed during the early days and the forum ended up using the default Latin1 characterset instead of the international UTF-8. In fact the first forum did not even have functional UTF-8 support. That the forum also failed to enforce even a specific characterset was troublesome because converting all posts to UTF-8 proved to be quite an ordeal as many posts actually contained multiple character encodings. Luckily, while a few posts ended up garbled, almost everything was moved successfully to UTF-8 over the course of a month (February 2009).