A blog (a truncation of the expression "weblog") is a discussion or informational website published on the World Wide Web consisting of discrete, often informal diary-style text entries (posts). Posts are typically displayed in reverse chronological order, so that the most recent post appears first, at the top of the web page. Until 2009, blogs were usually the work of a single individual, occasionally of a small group, and often covered a single subject or topic. In the 2010s, "multi-author blogs" (MABs) emerged, featuring the writing of multiple authors and sometimes professionally edited. MABs from newspapers, other media outlets, universities, think tanks, advocacy groups, and similar institutions account for an increasing quantity of blog traffic. The rise of Twitter and other "microblogging" systems helps integrate MABs and single-author blogs into the news media. Blog can also be used as a verb, meaning to maintain or add content to a blog.
The term "weblog" was coined by Jorn Barger 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. 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.
Early blogs were simply manually updated components of common Websites. In 1995, the "Online Diary" on the Ty, Inc. Web site was produced and updated manually before any blogging programs were available. Posts were made to appear in reverse chronological order by manually updating text based HTML code using FTP software in real time several times a day. To users, this offered the appearance of a live diary that contained multiple new entries per day. At the beginning of each new day, new diary entries were manually coded into a new HTML file, and the start of each month, diary entries were archived into its own folder which contained a separate HTML page for every day of the month. Then menus that contained links to the most recent diary entry were updated manually throughout the site. This text-based method of organizing thousands of files served as a springboard to define future blogging styles that were captured by blogging software developed years later.
The evolution of electronic and software tools to facilitate the production and maintenance of Web articles posted in reverse chronological order made the publishing process feasible to a much larger and less technically-inclined population. Ultimately, this resulted in the distinct class of online publishing that produces blogs we recognize today. For instance, the use of some sort of browser-based software is now a typical aspect of "blogging". Blogs can be hosted by dedicated blog hosting services, on regular web hosting services, or run using blog software.
After a slow start, blogging rapidly gained in popularity. Blog usage spread during 1999 and the years following, being further popularized by the near-simultaneous arrival of the first hosted blog tools.