A Blog or web log can be a single page of progressive additions or responses to a single topic. The topic may have an introduction to initiate a debate or just to introduce the blog. This could be in the form of a simple question, but can also be an audio file, a speech for example, a video or a presentation, combinations of these or just a single controversial image that inspires emotional debate. Blogs are often used as web diaries, for live events or project commentary and can include images, audio, video, presentations and / or links to websites or online documents. Blogs can be maintained by a single individual or allow entries from privileged users or can be fully open for anyone to comment. They can be moderated or fully open, private to subscribers or fully public for anyone to view. A blog as web content can be indexed by search engines and retrievable through thematic search queries directing to their website. This can be very interesting for an organisation to benefit from content developed free by the interested public through contributions to blogs, but disclaimers are advisory stating that comment does not reflect the opinion of the organisation.

Blogs are single web pages which can get very long and could also suffer from a short shelf life after which the content is of little real interest. This is specifically the case when the blog is a live commentary of an event.