A blog or web log is a website constructed as a journal or diary. It contains a series of posts or essays by the blogger (or blog author), organized chronologically. Some blogs also permit readers to post responses to particular blog entries. Blogs can deal with a particular consistent subject, or with whatever is on the mind of the blogger when he or she posts. Some blogs are updated on a regular schedule, others are irregular and unpredictable. In some cases, multiple bloggers share a single blog.