Personal blog - this is the most famous and widespread type of blog used in on the internet. This is defined as an online diary or journal where one person publishes their activities on a regular basis - usually daily.
Cultural blog - in a cultural blog the main theme revolves around music, arts, theater and popular culture.
Topic blog - a topic blog is similar to a niche search engine or forum. Writers publish information or articles about a very narrow topic. Examples of a narrow topic or niche would be breeding cocker spaniel dogs, or tropical fish health tips.
Business blog - a business blog focuses on subjects such as the stock market, financial markets and other business related topics. Business blogs can also be used to to promote businesses and to discuss topics in a forum type of environment.
Scientific blog - used to disseminate information and data. However, scientists only use blogs for basic scientific data and information. This is because they believe that the credibility of their projects may suffer if too much information is widely available.
Collaborative blog - this kind of blog is written by two or more writers. This type of blog is open for a variety of publishers to gather together and "brainstorm" ideas and concepts with others.
Eclectic blog - an eclectic blog is a place where information about a few specific topics are gathered together from various sources. Similar in nature to a niche blog it may be published by one or more people.
Well, that's a brief introduction to some of the different categories and types of blogs out on the internet. There are definitely more out there - see how many you can find as you make your way around the "bloggosphere"