* Primary source: If the blog is written by someone directly involved in an event, experiencing something firsthand, or presenting original research, it can be considered a primary source. For example, a war correspondent's blog from a conflict zone, a scientist's blog detailing their own experiments, or a politician's blog discussing their policy decisions would all be considered primary sources.
* Secondary source: If the blog summarizes, interprets, or analyzes information from other sources, it's a secondary source. For example, a blog that reviews books, analyzes a historical event based on existing research, or comments on news stories from other media outlets would be secondary.
Therefore, you must examine the content and authorship of a specific blog to determine its classification as a primary or secondary source.