Ratios, proportions, and percentages help us compare and measure things. This can help you measure popularity, or find how rare something might be, or see into the future by giving you a sense of how likely something is to happen.
Ratios and percents rock. You'll use them all the time.
Ratios and percentages show up everywhere. Anytime two or more quantities are compared, a ratio is there to lend a hand. Percents are particularly cool because "out of 100" is really easy to understand without much thought. If you hear that there's a 90% chance of rain, you'll probably know right away that it's time to grab the umbrella.
Here's an example taken from the news: