What Is A Blog?
A blog is used to write about anything, it’s a journal of sorts. You can include links to other sites, images, videos, news articles, news reports in video or audio format, etc. People can comment on your blog, which evokes conversation and essentially creates a community within your site. I wrote an article about a new search engine that is supposedly trying to compete with Google’s market share - cuil.com. I received 247 hits that day alone to my website -  solely because of the article. Blogs start with an existing framework (software) and can be customized to look exactly like your website.
 

What Is A Blog’s Purpose
In your blog you would write about things that are relevant to your business or hobbies. The goal is to give search engines more to index, thus serving more to searchers. Topics could be virtually anything that interests you. If you’re interested in the topic chances are someone else is too. Your opinions and advice are good when blogging - especially if you position yourself as a professional. The benefits are tremendous, and blogging is certainly the trend of today, and tomorrow!

David Meerman Scott, ex-director of marketing for Microsoft ­ now a consultant, wrote the book The New Rule of Marketing & PR. Essentially, it says blogging, podcasting, video-podcasting and social networking are the ways to market ­ not expensive media like billboards, print advertisements, radio spots and television commercials.