Here's a dry definition of a blog:
A blog is a web page that contains brief, discrete hunks of information called posts. These posts are arranged in reverse-chronological order (the most recent posts come first). Each post is uniquely identified by an anchor tag, and it is marked with a permanent link that can be referred to by others who wish to link to it.
That's what a blog is, but not what it's for. A blog is a means of communication, and there are many different types of messages carried by blogs. Some are nothing but pointers to other web sites, while others run long essays; some are personal diaries, others feature technology; some are edited by one person, others by teams.
This chapter is an introduction to the world of blogging. You'll learn key terms such as blog and syndication, see the different types of blog, analyze the ingredients of a blog, and compare and contrast the different ways you can run your own blog. After reading this chapter, you can make an intelligent decision on which blogging system to use and will know which of the later technology-specific chapters are for you.