Except, unlike money, posts mean nothing.
A post is a user-submitted message enclosed into a block containing the user's details and the date and time it was submitted. Members are usually allowed to edit or delete their own posts. Posts are contained in threads, where they appear as boxes one after another. The first post starts the thread; this may be called the TS (thread starter) or OP (original post). Posts that follow in the thread are meant to continue discussion about that post, or respond to other replies; it is not uncommon for discussions to be derailed.
On Western forums, the classic way to show a member's own details (such as name and avatar) has been on the left side of the post, in a narrow column of fixed width, with the post controls located on the right, at the bottom of the main body, above the signature block. In more recent forum software implementations the Asian style of displaying the members' details above the post has been copied.
Posts have an internal limit usually measured in characters. Often one is required to have a message of minimum length of 10 characters. There is always an upper limit but it is rarely reached – most boards have it at either 10,000, 20,000, 30,000, or 50,000 characters.
Most forums keep track of a user's postcount. The postcount is a measurement of how many posts a certain user has made. Users with higher postcounts are often considered more reputable than users with lower postcounts. Some forums have disabled postcounts in the hopes that doing so will reduce the emphasis on quantity over quality of information.