Blogs allow you to publish your thoughts like an online journal. A feed is essentially the product of the blog: a stream of blog posts. These posts can be categorized, searched, linked to, and commented on. All these functions are handled automatically by the blog software. View blog website samples.
As you can imagine, when maintaining a blog it helps to be able to write well, and you should follow some strategies for writing effectively for the web.
Blogs are very good for search engine rankings, and are most essential if you're in an industry that's competitive online. Blogs can be added to existing websites or created from the ground up.