A proportion is a way to show that two ratios are equal. A ratio is a comparison of two numbers, like 2 to 3 or 4 to 6. When you have two ratios that are the same, you have a proportion.
For example, let’s say you have 2 apples for every 3 oranges. You can write that as the ratio 2:3. If you also have 4 apples for every 6 oranges, that can be written as the ratio 4:6. Since both ratios are equal (2:3 is the same as 4:6), you can say that 2:3 = 4:6 is a proportion.
So, a proportion tells us that two different groups have the same relationship between their numbers!