Glossarytopic sentence
A topic sentence usually comes at the beginning of a paragraph; that is, it is usually the first sentence in a paragraph. Not only is a topic sentence the first sentence of a paragraph, but, more importantly, it is the most general sentence in a paragraph. What does "most general" mean? It means that there are not many details in the sentence, but that the sentence introduces what you are going to talk about in the paragraph.
If you want to read a more detailed description of writing a topic sentence click on the link below.