For example, imagine you run a food blog. You create recipes, write reviews for appliances, and share photography tips. These main topics (recipes, reviews, photography) are your blog categories. But within each topic fall a handful of sub-topics like bread and pastry recipes, small appliance and tool reviews, and low lighting and stop-motion photography tutorials.
If I’m visiting your site for dinner inspiration, I should be able to quickly click your recipes category to view all of the tasty options you have to offer.
No matter what kind of blog you run, the content you create needs to fall under one of your chosen categories.