What are they? 

Blog are web source written in diary-style, usually by a single author or group, that allows readers to add comments. Entries are usually listed from most to least recent and are added to regularly. Typically, it is easier to identify the author/creator of a blog.

How should they be evaluated?

• Does an identifiable author sign blog postings? 
• Is the author an expert on the topic? What are their credentials?
• Is there in-depth blog comments contributing to the topic?
• Are there regular new blog posts?

Take a few minutes to browse the blog linked on this page. What makes this blog credible?

Things to consider:

• Are the blog postings signed by an identifiable author?
• Are the blog postings authored by topic experts?
• Does the blog site provide the names of verifiable editors and contributors?

If answering yes to these considerations, chances are the blog is a credible source of information. If answering no, then you may want to consider an alternate source of information.