A blog is pieces of information or a discussion site that is being published on the internet. It consists of the discrete entries that are displayed typically in a reverse chronological order. Until 2009, blogs are usually the work of a single individual that is occasionally on the small group and usually covered on a single subject. More recently, the Multi-Author Blogs or the MABs was developed with post that are written by a large numbers of authors/writers and edited professionally. MABs from the newspapers and other media outlets, advocacy group, think tank, universities and similar institutions will account to the blog traffic’s increasing quantity.

The rise of Twitter and other microblogging systems are helping in the integration of MABs and single author blogs into the societal newstreams. Blog may be used as a verb which means maintaining or adding content to a blog. The growth and emergence of the blogs in the late 1990s have coincided with the advent of the web publishing tool, facilitating the content posting by the non-technical users. Most of them are interactive which allows the visitors to leave comments and even to message each other through GUI widgets on the blogs. This is also the interactivity which distinguishes them from the other static sites.

With this sense, blogging may be seen to be a type of social networking service. The bloggers are not only producing the content that they will post on their blogs but they are also building social relations with their readers and their co-bloggers. However, there are blogs that have high-readerships wherein they do not allow comments. Many blogs are providing commentary on a specific subject; others are functioning as more personal online diaries. There are also others that function more as a brand advertising online of a specific individual or company. A typical blog is combining images, text, and links into the other blogs, web pages and others of the media in relation to the topic. The capability of the readers to leave comments in a format that is interactive is a significant contribution to the popularity of various blogs.

Most of the blogs are mainly textual, even though some are focusing on photographs, art, videos, audio and music. Microblogging is another kind of blogging that features very short posts. In education, blogs may be used as instructional resources. These blogs are being referred to as edublogs. In February 2011, there are about 156 million of the public blogs that exists. By February 2014, there has been over 172 million Tumblr and 75.8 million in WordPress blogs existed all throughout the world. According to the critics and some other bloggers, Blogger is the most famous blogging service that is used these days. However, Blogger is not offering public statistics.

Types of Blogs
There are different types of blogs which differs not just on the kind of content but also in the way the content is written or being delivered.

There are some other types of blogs divided by categories like the blogs by device, by media type and the reverse blog.