What is discussion software?
To us, discussion software is a group of people interested in a common topic who are willing to type paragraphs to each other on a web page.
Yes, there is Twitter for very short form, there is web chat and IRC for real time with limited persistence, there is Tumblr for micro-blogging, and there are blogs for, well, blogging.
But we believe discussion software is a fundamental building block of web community.
via Discourse – About.