Many users do not bother to search a forum and directly create new threads to seek an answer to a question. On some forums, when the user types a new thread subject, the forum software brings up similar threads automatically on the side. This helps keep the number of redundant threads (or the overall forum pollution) to a lower level as users who neglect to search for a topic and are posting a thread may find the answer to their question as they are creating the new thread. Instead of having to search the forum, and then creating a thread if there is no satisfying answer, duplicate thread prevention allows the user to go and seek the answer to a topic. An example is Stack Overflow.
Most forums provide an option for the forum owner to customize the look and feel. Some forums also allow the administrator to create multiple styles or themes, and allow the user to choose which one they wish to view. Themes may simply be a different set of colors and graphics, or they may involve a different layout to the forum, such as one optimized for small-screen devices.
Some forums provide calendar functionality for storing events and appointments, either per-user or as a forum-wide shared calendar.
Most forums provide the option for a user to upload an image along with a message posting. This is usually accompanied by a space limit (e.g. 1MB per user) to prevent users from filling up the forum host's webspace. Some forums also allow other types of files to be uploaded. Some allow inline linking to images hosted on image hosting services.
One major usability issue is whether images can be uploaded to a forum and displayed inline in message postings easily (or at all). The presence of "image attachment uploading" does not imply that in-message display of images within the flow of message text is possible (or if possible, easy to achieve).
Unread message tracking refers to the way that is used by forum software to track and display messages that have not yet been read by the current user. This can be one of the following:
Most forums are at risk of continuous attack by forum spammers, largely promoting websites with no relevance to the forum's niche. Systems vary in how they are geared to defense, and checking the offering is an important consideration before selection. A forum cannot succeed unless there is an effective system of defense, and an efficient set of tools for spam removal.
CAPTCHAs are a common featu