There are various types of blogs, and each differs in the way content is delivered or written.
By media type
A blog comprising videos is called a vlog, one comprising links is called a linklog, a site containing a portfolio of sketches is called a sketchblog or one comprising photos is called a photoblog. Blogs with shorter posts and mixed media types are called tumblelogs.
An Artlog is a form of art sharing and publishing in the format of a blog, but differentiated by the predominant use of and focus on Art work rather than text.
A rare type of blog hosted on the Gopher Protocol is known as a Phlog
Blogs can also be defined by which type of device is used to compose it. A blog written by a mobile device like a mobile phone or PDA is called a moblog.
Some blogs focus on a particular subject, such as political blogs, travel blogs, fashion blogs, project blogs, niche blogs, classical music blogs, legal blogs (often referred to as a blawgs) or dreamlogs. While not a legitimate type of blog, one used for the sole purpose of spamming is known as a Splog. A Slog (Site or website log) is a section or 'slice' of a regular business website, which is seamlessly integrated within the regular website structure but is produced with blogging software.
Legal status of publishers
A blog can be private, as in most cases, or it can be for business purposes. Blogs, either used internally to enhance the communication and culture in a corporation or externally for marketing, branding or PR purposes are called corporate blogs.
Blog search engines
Several blog search engines are used to search blog contents (also known as the blogosphere), such as blogdigger, Feedster, and Technorati. Technorati provides current information on both popular searches and tags used to categorize blog postings.
Blogging Communities and Directories
Several online communities exist that connect people to blogs and bloggers to other bloggers, including BlogCatalog and MyBlogLog. A collection of local blogs is sometimes referred to as a Bloghood.
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 (now known as Izea) a large number of 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.
Blurring with the mass media
Many bloggers, particularly those engaged in participatory journalism, differentiate themselves from the mainstream media, while others are members of that media working through a different channel. Some institutions see blogging as a means of "getting around the filter" and pushing messages directly to the public. Some critics worry that bloggers respect neither copyright nor the role of the mass media in presenting society with credible news. Bloggers and other contributors to user generated content are behind Time magazine naming their 2006 person of the year as "you".
Many mainstream journalists, meanwhile, write their own blogs — well over 300, according to CyberJournalist.net's J-blog list. The first known use of a weblog on a news site was in August 1998, when Jonathan Dube of The Charlotte Observer published one chronicling Hurricane Bonnie.
Blogs have also had an influence on minority languages, bringing together scattered speakers and learners; this is particularly so with blogs in Gaelic languages, whose creators can be found as far away from traditional Gaelic areas as Kazakhstan and Alaska. Minority language publishing (which may lack economic feasibility) can find its audience through inexpensive blogging.
There are many examples of bloggers who have published books based on their blogs, e.g., Salam Pax, Ellen Simonetti, Jessica Cutler, ScrappleFace. Blog-based books have been given the name blook. A prize for the best blog-based book was initiated in 2005, the Lulu Blooker Prize. However success has been elusive offline, with many of these books not selling as well as their blogs. Only sex blogger Tucker Max cracked the New York Times Bestseller List.