A topic sentence is the most important sentence in a paragraph. It tells the reader what the paragraph is about. In academic and formal writing in English, every paragraph should begin with a clear topic sentence.

The topic sentence introduces the main idea or goal of the paragraph. It tells the reader what to expect and helps keep the paragraph focused. All the other sentences in the paragraph should support, explain, or give evidence for the idea in the topic sentence.

A good topic sentence is…

Not too broad:
❌ The internet is important.
✅ The internet has changed how students find and use information for school.

Not too narrow:
❌ Google was created in 1998 by Larry Page and Sergey Brin.
✅ Search engines like Google help students do academic research more efficiently.

Just right:
Topic Sentences introduce an idea that can be supported and discussed with several supporting sentences (a paragraph-amount of information).