Perhaps it would be better to start off with the question of what is a web host. Normally when you ask this question, you either get a very over simplistic answer or one steeped in techno speak that makes you wish you hadn't asked it in the first place. It is an important question for anyone who owns a website or blog, because it does directly affect both short term and long term viability and costs of your site. Many blogs are hosted by companies, like Typepad and blogger, and they are fairly transparent about costs, features , design etc. 
They are pretty stable companies behind them and one of the reasons people use them in the first place is that they are self hosted, so people don't have to worry about any of that stuff in the first place. The issue of hosting becomes more important when talking about Wordpress blogs and a lot of standard websites. Wordpress has become the blog and website of choice for a lot of people, largely because it is very easy to use, once you understand it, and has enormous capabilities. Having a reliable company who effectively runs your site behind the scenes is really important. Nowadays there area number of companies, perhaps Hostgator and Bluehost being the two best known, who offer really good deals in terms of products, but also offer through a script called Fantastico, a virtually instantaneous installation of Wordpress. That of itself is almost worth a monthly sub !
A reliable host matters, because if you go for the cheap option, without the name behind it, then inevitably you'll regret it. Do a search of online webmaster discussion groups and forums, and see who they are using and who they would recommend - you can't do better than that.They are pretty stable companies behind them and one of the reasons people use them in the first place is that they are self hosted, so people don't have to worry about any of that stuff in the first place.
