The word blog is a conflation of two words: Web and log. It contains in its four letters a concise and accurate self-description: it is a log of thoughts and writing posted publicly on the World Wide Web. In the monosyllabic vernacular of the Internet, Web log soon became the word blog.
This form of instant and global self-publishing, made possible by technology widely available only for the past decade or so, allows for no retroactive editing (apart from fixing minor typos or small glitches) and removes from the act of writing any considered or lengthy review. It is the spontaneous expression of instant thought—impermanent beyond even the ephemera of daily journalism. It is accountable in immediate and unavoidable ways to readers and other bloggers, and linked via hypertext to continuously multiplying references and sources. Unlike any single piece of print journalism, its borders are extremely porous and its truth inherently transitory. The consequences of this for the act of writing are still sinking in.
more from The Atlantic Monthly here.