A blog (an abridgment of the term web log) is a website where entries are commonly displayed in reverse chronological order. "Blog" can also be used as a verb, meaning to maintain or add content to a blog.
Many blogs provide commentary or news on a particular subject; others function as more personal online diaries. A typical blog combines text, images, and links to other blogs, web pages, and other media related to its topic. The ability for readers to leave comments in an interactive format is an important part of many blogs. Most blogs are primarily textual, although some focus on art (artlog), photographs (photoblog), sketchblog, videos (vlog), music (MP3 blog), audio (podcasting) are part of a wider network of social media. Micro-blogging is another type of blogging which consists of blogs with very short posts. As of December 2007, blog search engine Technorati was tracking more than 112 million blogs.
Before blogging became popular, digital communities took many forms, including Usenet, commercial online services such as GEnie, BiX and the early CompuServe, e-mail lists and Bulletin Board Systems (BBS). In the 1990s, Internet forum software, such as WebEx, created running conversations with "threads". Threads are topical connections between messages on a metaphorical "corkboard". Some have likened blogging to the Mass-Observation project of the mid-20th century.
In 2004, the role of blogs became increasingly mainstream, as political consultants, news services and candidates began using them as tools for outreach and opinion forming. Even politicians not actively campaigning, such as the UK's Labour Party's MP Tom Watson, began to blog to bond with constituents.
Minnesota Public Radio broadcast a program by Christopher Lydon and Matt Stoller called "The blogging of the President," which covered a transformation in politics that blogging seemed to presage. The Columbia Journalism Review began regular coverage of blogs and blogging. Anthologies of blog pieces reached print, and blogging personalities began appearing on radio and television. In the summer of 2004, both United States Democratic and Republican Parties' conventions credentialed bloggers, and blogs became a standard part of the publicity arsenal. Mainstream television programs, such as Chris Matthews' Hardball, formed their own blogs. Merriam-Webster's Dictionary declared "blog" as the word of the year in 2004.
In 2004, Global Voices Online, a site which "aggregates, curates, and amplifies the global conversation online – shining light on places and people other media often ignore" surfaced, bringing to light bloggers from around the world. Today, the site has a relationship with Reuters and is responsible for breaking many global news stories.
Blogs were among the driving forces behind the "Rathergate" scandal, to wit: (television journalist) Dan Rather presented documents (on the CBS show 60 Minutes) that conflicted with accepted accounts of President Bush's military service record. Bloggers declared the documents to be forgeries and presented evidence and arguments in support of that view, and CBS apologized for what it said were inadequate reporting techniques (see Little Green Footballs). Many bloggers view this scandal as the advent of blogs' acceptance by the mass media, both as a news source and opinion and as means of applying political pressure.
Some bloggers have moved over to other media. The following bloggers (and others) have appeared on radio and television: Duncan Black (known widely by his pseudonym, Atrios), Glenn Reynolds (Instapundit), Markos Moulitsas Zúniga (Daily Kos), Alex Steffen (Worldchanging) and Ana Marie Cox (Wonkette). In counter-point, Hugh Hewitt exemplifies a mass media personality who has moved in the other direction, adding to his reach in "old media" by being an influential blogger.
Some blogs were an important news source during the December 2004 Tsunami such as Medecins Sans Frontieres, which used SMS text messaging to report from affected areas in Sri Lanka and Southern India. Similarly, during Hurricane Katrina in August 2005 and the aftermath a few blogs which were located in New Orleans, including the Interdictor and Gulfsails were able to maintain power and an Internet connection and disseminate information that was not covered by the Main Stream Media.
In the United Kingdom, The Guardian newspaper launched a redesign in September 2005, which included a daily digest of blogs on page 2. Also in June 2006, BBC News launched a weblog for its editors, following other news companies.
In January 2005, Fortune magazine listed eight bloggers that business people "could not ignore": Peter Rojas, Xeni Jardin, Ben Trott, Mena Trott, Jonathan Schwartz, Jason Goldman, Robert Scoble, and Jason Calacanis.
In 2007, Tim O'Reilly proposed a Blogger's Code of Conduct.
Recently, 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.
Recently, through the mass popularity of sponsored post ventures such as PayPerPost many personal blogs have started writing sponsored posts for advertisers wanting to boost buzz about new products and services. It has revolutionised the blogosphere almost in the same way that Google AdSense did.
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 thus 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 also 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 listed the most linked-to blog as that of Chinese actress Xu Jinglei and the most-read blog as group-written Boing Boing.
Gartner forecasts that blogging will peak in 2007, leveling off when the number of writers who maintain a personal website 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.
It was reported by Chinese media Xinhua that the blog of Xu Jinglei received more than 50 million page views, claiming to be the most popular blog in the world. In mid-2006, it also had the most incoming links of any blogs on the Internet.