A ratio is a way of comparing two quantities by showing how many times one contains the other, or how they relate in size. If a recipe calls for a ratio of 2 cups of flour to 1 cup of sugar, you're using twice as much flour as sugar. If your class has 15 girls and 10 boys, the ratio of girls to boys is 15 to 10 (which simplifies to 3 to 2).

Ratios appear everywhere once you start noticing them. A basketball player's free throw ratio might be 8 makes out of 10 attempts. A painter mixing colors needs the right ratio of blue to yellow to get the perfect shade of green. Engineers designing bridges calculate ratios to ensure structures are strong enough to hold their weight.

You can write ratios in different ways: 3 to 2, 3:2, or as a fraction (3/2). The order matters. A ratio of flour to sugar (2:1) is different from sugar to flour (1:2).

The word also appears in everyday speech. On social media, when someone posts something foolish and gets far more critical replies than likes, people say they “got ratioed.” This usage comes from the idea that the ratio of negative to positive responses is lopsided. Understanding ratios helps you see relationships between numbers and make fair comparisons in everything from cooking to sports to science experiments.