What is blog?
A blog (short for weblog) is a personal online journal that is frequently updated and intended for general public consumption. Blogs are defined by their format: a series of entries posted to a single page in reverse-chronological order.Blogs generally represent the personality of the author or reflect the purpose of the Web site that hosts the blog. Topics sometimes include brief philosophical musings, commentary on Internet and other social issues, and links to other sites the author favors, especially those that support a point being made on a post.
resource : http://searchwindevelopment.techtarget.com/definition/blog
Why do we blog??
"In terms of why people blog, well, my belief is that it's to have a voice, however small. To think that just like the people who write those fancy opinion columns for The New York Times and the Wall Street Journal, you too can share your thoughts, vent, and complain to the public at large. Having said that, there are lots of really smart bloggers who have interesting perspectives on the news, politics, sports, business, etc., people who wouldn't otherwise be heard in mainstream media.
"That's why I read blogs, about 150/daily, and that's why I write my own blogs too. Of my own blogs, perhaps the most interesting to your readers are both The Intuitive Life Business Blog, which is where I talk about the business of the Internet and how blogging can be an extraordinarily effective marketing channel, and APparenting.com, where my wife and I share real life stories of parenting in this modern world. "Sometimes I'll write something and never get a response from anyone, but other times I'll write about something like an ethical challenge for a Fortune 500 business or the lame excuses men use for cheating on their spouse, and it'll garner dozens or even hundreds of comments from other people, readers who share perspectives I never knew.