A blog is a website where entries are written in chronological order and commonly displayed in reverse chronological order. (Wikipedia)
Typically a blog contains text, photos, and links to other web pages.
Often there is a way for readers to leave comments.
Usually there is an RSS feed which allows readers to subscribe to the blog. An RSS feed brings the new entries to you, rather than you having to go to look and see if there is a new entry.
People use blogs as an online journal to share with family and friends.
So how does one keep up with new content on blogs without having to check each one each day?
You use an aggregator (RSS feed reader). An aggregator is a web page that keeps track when blogs that interest you are updated.
I use Bloglines to keep track of over a 100 blogs. I use my blogline page as my homepage when I open my web browser. A quick scan let me know what blogs have new updates, and I can skim through the content without even going to the blog.
Lewis Elementary - Principal Tim Wilson has set up their school web page as a blog. Notice that the top banner image changes each time you load the page.
ePals - I have created a schoool account here, but haven't tried much with it. It is geared for kids, no ads. This might be a good solution if you want to set up blogs for students to use.
Create your own free wiki!