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^[14] and Bulletin Board Systems (BBS). In the 1990s, Internet forum software, created running conversations with "threads". Threads are topical connections between messages on a virtual "corkboard".
From 14 June 1993 Mosaic Communications Corporation maintained their "What’s New"^[15] list of new websites, updated daily and archived monthly. The page was accessible by a special "What's New" button in the Mosaic web browser.
The modern blog evolved from the online diary, where people would keep a running account of their personal lives. Most such writers called themselves diarists, journalists, or journalers. Justin Hall, who began personal blogging in 1994 while a student at Swarthmore College, is generally recognized as one of the earlier bloggers,^[16] as is Jerry Pournelle.^[17] Dave Winer's Scripting News is also credited with being one of the older and longer running weblogs.^[18][19] The Australian Netguide magazine maintained the Daily Net News^[20] on their web site from 1996. Daily Net News ran links and daily reviews of new websites, mostly in Australia. Another early blog was Wearable Wireless Webcam, an online shared diary of a person's personal life combining text, video, and pictures transmitted live from a wearable computer and EyeTap device to a web site in 1994. This practice of semi-automated blogging with live video together with text was referred to as sousveillance, and such journals were also used as evidence in legal matters.

The term "weblog" was coined by Jorn Barger^[9] on 17 December 1997. The short form, "blog", was coined by Peter Merholz, who jokingly broke the word weblog into the phrase we blog in the sidebar of his blog Peterme.com in April or May 1999.^[10][11][12] Shortly thereafter, Evan Williams at Pyra Labs used "blog" as both a noun and verb ("to blog", meaning "to edit one's weblog or to post to one's weblog") and devised the term "blogger" in connection with Pyra Labs' Blogger product, leading to the popularization of the terms.^[13]

Many blogs provide commentary on a particular subject; others function as more personal online diaries; others function more as online brand advertising of a particular individual or company. A typical blog combines text, images, and links to other blogs, Web pages, and other media related to its topic. The ability of readers to leave comments in an interactive format is an important contribution to the popularity of many blogs. Most blogs are primarily textual, although some focus on art (art blogs), photographs (photoblogs), videos (video blogs or "vlogs"), music (MP3 blogs), and audio (podcasts). Microblogging is another type of blogging, featuring very short posts. In education, blogs can be used as instructional resources. These blogs are referred to as edublogs.
On 16 February 2011, there were over 156 million public blogs in existence. On 20 February 2014, there were around 172 million Tumblr^[4] and 75.8 million WordPress^[5] blogs in existence worldwide. According to critics and other bloggers, Blogger is the most popular blogging service used today, however Blogger does not offer public statistics.^[6][7] Technorati has 1.3 million blogs as of February 22, 2014^[8]