A blog is a website or online journal that is regularly updated with content about a specific topic. Blogs are often written in a conversational style and presented in reverse chronological order. The word "blog" is short for "weblog" and is a combination of the words "web" and "log". 

Blogs can be personal or professional, and can cover a wide range of topics, such as fashion, technology, politics, business, or lifestyle. For example, a personal blog could be like a digital diary, while a professional blog could focus on a specific area. Blogs can be used as a platform for individuals or organizations to share their ideas, thoughts, and information with a wider audience. They can also be interactive, with sections at the bottom of posts where readers can leave comments. 

Blogs can be hosted on websites, but they are distinct from websites, which are groups of connected web pages that contain more information about a business or organization.