Community and Cataloging

The Blogosphere
The collective community of all blogs is known as the blogosphere. Since all blogs are on the internet by definition, they may be seen as interconnected and socially networked. Discussions "in the blogosphere" have been used by the media as a gauge of public opinion on various issues. A collection of local blogs is sometimes referred to as a bloghood.

Blog Search Engines
Several blog search engines are used to search blog contents, such as Bloglines, BlogScope, and Technorati. Technorati, which is among the most popular blog search engines, provides current information on both popular searches and tags used to categorize blog postings. Research community is working on going beyond simple keyword search, by inventing new ways to navigate through huge amounts of information present in the blogosphere, as demonstrated by projects like
BlogScope.{{fix|link=Wikipedia:Citation needed|text=citation needed}

Blogging Communities and Directories
Several online communities exist that connect people to blogs and bloggers to other bloggers, including BlogCatalog and MyBlogLog.

Blogging and Advertising
It is common for blogs to feature advertisements either to financially benefit the blogger or to promote the blogger's favorite causes. The popularity of blogs has also given rise to "fake blogs" in which a company will create a fictional blog as a marketing tool to promote a product.

Popularity
Researchers have analyzed the dynamics of how blogs become popular. There are essentially two measures of this: popularity through citations, as well as popularity through affiliation (i.e. blogroll). The basic conclusion from studies of the structure of blogs is that while it takes time for a blog to become popular through blogrolls, permalinks can boost popularity more quickly, and are perhaps more indicative of popularity and authority than blogrolls, since they denote that people are actually reading the blog's content and deem it valuable or noteworthy in specific cases.

The blogdex project was launched by researchers in the MIT Media Lab to crawl the Web and gather data from thousands of blogs in order to investigate their social properties. It gathered this information for over 4 years, and autonomously tracked the most contagious information spreading in the blog community, ranking it by recency and popularity. It can therefore be considered the first instantiation of a memetracker. The project is no longer active, but a similar function is now served by tailrank.com.

Blogs are given rankings by Technorati based on the number of incoming links and Alexa Internet based on the Web hits of Alexa Toolbar users. In August 2006, Technorati found that the most linked-to blog on the internet was that of Chinese actress Xu Jinglei. Chinese media Xinhua reported that this blog received more than 50 million page views, claiming it to be the most popular blog in the world. Technorati rated Boing Boing to be the most-read group-written blog.

Gartner forecasts that blogging will peak in 2007, leveling off when the number of writers who maintain a personal Web site reaches 100 million. Gartner analysts expect that the novelty value of the medium will wear off as most people who are interested in the phenomenon have checked it out, and new bloggers will offset the number of writers who abandon their creation out of boredom. The firm estimates that there are more than 200 million former bloggers who have ceased posting to their online diaries, creating an exponential rise in the amount of "dotsam" and "netsam" —that is to say, unwanted objects on the Web (analogous to flotsam and jetsam).