Forum is an online discussion site where users create profiles and communicate with each other on the web.
Before a prospective member joins a forum and makes posts to others, they are usually required to register. In general they are required to create an online identity (nickname) to be used on the forum. After a member is approved by the administrator or moderator of the forum, you will be able to log in the forum, read what has previously been posted, start your own discussions or reply to discussions already started. Some forums allow "Guest" access so you can view the forum before joining. This is a good way to check out a forum before you decide if you want to join. You will not be able to actively participate in most forums as a guest.
The separate conversations in an Internet forum are called threads. Threads are made up of member-written posts. Internet forum members can usually edit their own posts, start new topics, post in their choice of threads and edit their profile. A profile usually lists optional information about each forum member such as the city they are located in and their interests. A forum administrator can usually modify threads as well as move or delete threads if necessary.
Forums are existing in niches with relevant and related content and audiences; they often provide destinations for help with specific problems, current trends within your industry. In SEO terms content on the forum consists of user-generated long-tail queries which if optimized rightly can provide you with both visitors and inbound links.