¿What's a Blog?

A Blog or Weblog is a web page where the author(s) periodically publishes little articles (Posts) about any issue, where those posts can be commented by more people

Blogs can be used for many other goals, as an informative tool, denounce, or simply to express something to share with others.

Allowing posts comments to other blogs owners, creates virtual networks of people who generate conversation about specific issues.

Definition of Weblog on the Wikipedia