According to Wiki...
A blog (a contraction of the term "Web log") is a Web site, usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in reverse-chronological order. "Blog" can also be used as a verb, meaning to maintain or add content to a blog.
More specifically...
A photoblog (a.k.a. photolog or phlog) is a form of photo sharing and publishing in the format of a blog, but differentiated by the predominant use of and focus on photographs rather than text. Photoblogging (the action of posting photos to a photoblog) gained momentum in the early 2000s with the advent of the moblog and cameraphones.
