Reasons for this expansion are different. First, blog represents very simple tool for individuals and organizations to use computers and Internet for self presentation and work promotion to widest possible auditorium, the whole world. Never before in the history of human society existed such a possibility considering usage of very little resources. All you need is a computer or even only mobile phone and access to global network. Possibility that anyone can become blogger in few minutes using free web services like Blogger, Wordpress or Typepad is another reason for existence of huge number of blogs.
image by Nawal_
We shouldn't forget another important factor which specially lately has big role and that is blog monetization and creation of new chances for earning online.
Blogosphere, as collection of all blogs is very dynamic system. It's growth is very hard to track because of enormous volume, but some innovations are still predictable and certain. One of them is birth and development of group blogging as response to big competitiveness in some categories.
Group blogging is feature when more authors (often from distant parts of the world) come together in blogging on one project. That project can be single blog with specific niche or few different blogs.
We can make an analogy in some sense with database theory. Until recently popular relations were one author one blog and one author many blogs more often. Group blogging brings new relations like many authors one blog and many authors many blogs.
Group blogging advantages outnumber group blogging problems, but we shouldn't neglect either side.
