Forum posting refers to posting in various forums with signature links. They provide 'no follow' backlinks that are useful to build your website traffic from various sources.
Within a forum's topic, each new discussion started is called a thread, and can be replied to by as many people as so wish. Depending on the forum's settings, users can be anonymous or have to register with the forum and then subsequently log in in order to post messages.
Forum posting/commenting is basically a platform where we can share ideas and information. It is an off page SEO technique that helps in making engagement with people and for getting quality backlinks for your website.
Technology today has reached a level where all information is handy. With more and more people becoming active on web, there is a huge flow of information from one another. This information exchange paved the way for the online forums. Forums also provide a stage to social networking by means of information exchange.