A blog is a website consisting of entries or posts displayed in reverse chronological order. Blogs allow for user interactivity through features like comments and links. There are several reasons to start a blog including keeping your website fresh for search engines like Google and making it easier for people to find you online. The document provides steps for setting up a blog including choosing a name and software, deciding on a design, hosting the blog, and establishing a content strategy. It emphasizes the importance of consistent, persistent content and thinking locally for real estate blogs.