• Rub virtual elbows with people who share the same interest(s) that you do
• Bounce ideas back and forth and stimulate your creativity
• Learn from the masters of a field
• Share your own knowledge with others
• Express yourself or gain exposure for your ideas, site, or creative endeavors

Finding forums is as easy as typing a few words into a search engine. Finding the right forum takes a little more thought and effort. Here are some criteria you might want to consider:

1. Subject Matter

There are discussion forums for just about every topic imaginable. Beyond finding a forum geared towards the general area you are interested in, how wide or narrow a forum is can be worth paying attention to. If you are interested in classical music, for instance, a general music forum might be ok, but a classical music forum might be better. On the other hand, you might find that a forum focused only on a Beethoven is too narrow.

2. Culture/Management/Rules

Some forums have very strict rules as to what you can and can't say in posts. Others allow just about anything. Some are friendly, relaxed places. Others have their share of rude people and strife. In some, posts are answered promptly and intelligently. In others, you see a lot of questions with few responses. Site moderators vary in their degrees of skill and helpfulness. A good question to ask yourself when evaluating a forum is whether the conversations taking place are the type in which you would like to participate.

What the rules and practice towards commercial messages are is an important area too. Most people find commercial messages from other users unrelated to the forum's supposed purpose (commonly referred to as "forum spam") to be a definite negative. At the other end of the spectrum, you might not want to join a forum that bans links in signatures if one of your primary interests is promoting your blog or website.

3. Size

Forums come in all sizes. Some have thousands of active members, whereas in others you can count the active members on one hand. What size is best depends on your needs and preferences. A forum with a huge number of members will usually tend to have more variety and knowledge available, all other things being equal, than a smaller forum. On the other hand, a smaller forum is easier to keep up with and you might enjoy being a "big fish in a small pond".

4. Style/Software/Etc.

Different forums have different layouts and features. All other things being equal, a forum with a set of screens, buttons, menus, and features that you find sensible and useful is better than one where you find the arrangement to be just annoying or confusing.

5. Site Responsiveness

Like websites in general, forums vary greatly in how fast the pages load. Some load quickly and uneventfully. Others do not and are prone to displaying messages like "the forum is overstressed now, please try again in later" or something along those lines. Then there are the forums where the site crashes for days at a time, leaving one to think (sometimes accurately) that the site might never come back online. How glitch-prone a forum is or is not is definitely a factor to consider.

Of course, all of these areas need to be evaluated on an ongoing basis. It is possible for forum with problems in site responsiveness to get better with the right upgrades or tweaks, or a forum can start crashing/glitching as the user base grows beyond the capability of the infrastructure to handle it. New subtopics can be added to a forum (or taken away). Rules (and forum ownership/management) can change. If things change for the better, that's well and good. If they change for the worse, then it might be time to start looking for a new forum again :).