A Venn diagram is useful for showing how two things are alike and different. It was named after John Venn, who invented it 1880.

Suppose you wanted to compare and contrast alligators and crocodiles. Follow these steps to construct a Venn diagram.

• Step 1. Read to learn all you can about alligators and crocodiles. As you read, list the important characteristics of each on a sheet of paper.
• Step 2. Draw two overlapping circles on a different sheet of paper. Label the left circle as "Alligators," and the right circle as "Crocodiles."
• Step 3. Refer to your list of characteristics of alligators and crocodiles. Look for ways in which they are alike. Write these similarities in the overlap section between the two circles.
• Step 4. Referring back to your list of characteristics of alligators, write the unique ones in the left circle.
• Step 5. Referring back to your list of characteristics of crocodiles, write the unique one in the right circle.

Here is what your Venn diagram might look like when you complete these steps.

The completed Venn diagram provides a comparison and contrast of alligators and crocodiles at a glance. It can serve as the starting point for writing a paper, and as a good review tool for tests. You can create Venn diagrams to compare and contrast many pairs of things.