Traffic assignment is like a game where you try to figure out which roads people will use to get from one place to another.
Imagine you and your friends need to go to a park to play. There are three different roads that go to the park: a big one, a medium one, and a small one. Now let's say there are twenty of you and you can't all fit in one car. Some of you will take the big road because it can handle more cars at once. Others might take the medium road because it's faster. And maybe a few brave souls will take the small road because it's the only one that goes past an ice cream shop.
Traffic assignment is kind of like this game, but instead of friends going to the park, we're talking about thousands or even millions of people driving on roads every day. Experts use math and computer models to figure out which roads people are likely to use based on things like distance, congestion, speed, and convenience. This helps transportation planners to design roads and highways that can handle the amount of traffic and keep things moving smoothly.