Spamming a message board forum, in general, is when a user posts something which is off-topic or doesn’t have anything to do with the current subject. Also, a post that doesn’t contribute to the thread whatsoever is also considered spam in some cases.

Another form of Forum Spamming is where a person repeatedly posts about a certain subject in a manner that is unwanted by (and possibly annoying to) the general population of the forum.

Lastly, there is also the case where a person posts messages solely for the purpose of increasing the number of his or her posts on the forum.

In a broader sense, advertising on forums where it is not wanted is known as spamming and is generally seen as an annoyance.