Wikipedia gives this definition (http://en.wikipedia.org/wiki/Blogosphere):
The blogosphere is made up of all blogs and their interconnections. The term implies that blogs exist together as a connected community (or as a collection of connected communities) or as a social network in which everyday authors can publish their opinions.
The key idea is connectivity. The Wikipedia definition is concerned with the connectivity between blogs, which is something we will be exploring here. However, I would also widen this definition to include the connectivity between blogs and their readers. They are as much a part of the blogosphere as the bloggers themselves. The readers are the glue that holds together all the connections in the blogosphere. This is particularly true of the avid blog readers, who...