Blogs are simply web logs. Think of them as online journals, diaries, or interactive logs. Blog may contain text, graphics, photos, audio, video, and other elements. Blogs are normally run by a single author who writes and posts the entries. The blog author may open their blog to comments from members of a group, registered participants, or anyone. Taken from http://escrapbooking.com/blogging/basics.htm

Blogs are web logs that are updated regularly, usually on a daily basis. They contain information related to a specific topic. In some cases blogs are used as daily diaries about people's personal lives, political views, or even as social commentaries. The truth of the matter is that blogs can be shaped into whatever you, the author, want them to be. Taken from http://www.rss-specifications.com/everything-blogs.htm

Ten Reasons why Blogging Might be Good for You (and possibly for your Career):

1. Keeping a blog means you generally end up learning a little HTML, a little CSS, a little web design, and a little about web interactivity (i.e. comments, RSS, etc.). These are good things to know, and might come in handy.

2. Writing is a good skill. Blogs are generally text, and any bit of practice writing is a good thing for you professionally as well as personally.

3. Keeping a blog might make you more likely to read blogs or keep up with what's new via the internet. This may or may not prompt you to think about things you would not have thought about otherwise. Even a slight chance of prompting new thinking is a good thing.

4. Blogging can help you sort out your ideas, build on them, and come up with new ones. This is also true of keeping a paper journal. However, if anyone happens to have read your blog and given you some feedback, your ideas might have been honed and changed in the process.

5. You can put a well-designed, well-constructed blog on your resume.

6. Your supervisor, potential employer, instructor, or other important person might one day come across your blog, read a few posts, and think that you are an interesting/intelligent person who deserves more attention/money.

7. Having a blog and using your real name means that you will have a least one real result on Google when someone searches for your name. It may never be the first option, particularly if your name is John Smith or something similarly common.

8. Blogging software is just content management software; understanding ways to manage information may come in handy professionally. Or not.

9. You'll always have an archive of ideas at your fingertips. That is, if you consistently blog about your ideas.

10. Your exes can follow your life from a distance without calling you in a drunken stupor to find out what you're up to.
Taken from http://mazar.ca/archives/2005/03/ten_reasons_why.html