Double posting

One common faux pas on Internet forums is to post the same message twice. Users sometimes post versions of a message that are only slightly different, especially in forums where they are not allowed to edit their earlier posts. Multiple posting instead of editing prior posts can artificially inflate a user's post count. Multiple posting can be unintentional; a user's browser might display an error message even though the post has been transmitted or a user of a slow forum might become impatient and repeatedly hit the submit button. Multiple posting can also be used as a method of trolling or spreading forum spam. A user may also send the same post to several forums, which is termed crossposting. The term derives from Usenet, where crossposting was an accepted practice but causes problems in web forums, which lack the ability to link such posts so replies in one forum are not visible to people reading the post in other forums.

Necroposting

A necropost is a message that revives (as in necromancy) an arbitrarily old thread, causing it to appear above newer and more active threads. This practice is generally seen as a breach of netiquette on most forums. Because old threads are not usually locked from further posting, necroposting is common for newer users and in cases where the date of previous posts is not apparent.

Word censor

Main article: Scunthorpe problem

A word censoring system is commonly included in the forum software package. The system will pick up words in the body of the post or some other user-editable forum element (like user titles), and if they partially match a certain keyword (commonly no case sensitivity) they will be censored. The most common censoring is letter replacement with an asterisk character. For example, in the user title, it is deemed inappropriate for users to use words such as "admin", "moderator", "leader" and so on. If the censoring system is implemented, a title such as "forum leader" may be filtered to "forum ******". Rude or vulgar words are common targets for the censoring system.[23][24] But such auto-censors can make mistakes, for example censoring "wristwatch" to "wris****ch" and "Scunthorpe" to "S****horpe."