We often get asked exactly what a blog is, how to manage one, and whether it is better for it to be on your own domain or on something like Typepad or Blogger.
Well, a blog is simply a publishing system. The beauty of it is that it categorises itself as you add new articles, and create the categories or tags you want to associate the article with. The nature of blogging is that it does not need to be formal. It is a great way to talk to your customers, publish thought-leaders, or just link to something interesting or amusing you have found elsewhere on the web. Blogs are a great SEO tool as well — naturally optimised for search engines, they also notify Google of news articles as soon as they are posted meaning your article is listed very quickly.
Our view is that the blog should be part of your own site: the content you add to your blog will (or should) be relevant to your market(s) and hence adds more authority to your domain — the search engines will see your website as being more relevant to that topic than a site with little content.
An integrated blog also adds more credibility that you are a serious business and not a fly-by-night.
With the fantastic WordPress software being free, and easily customised, there is no excuse really.
This article from e-consultancy echoes our views and provides some more useful answers to your blogging questions.