Context-adaptive variable-length coding

Imagine you have a bunch of pictures and you want to send them to your friend over the internet. But you don't want it to take too long, so you make the pictures smaller by squeezing them. But squeezing them makes them harder to understand.

So, to make the pictures easier to understand again, you use something called "context-adaptive variable-length coding". This means that instead of just squeezing the pictures, you also change the way that the information in the pictures is stored.

It's like if you were writing a story and you told your friend that every time they see the letter "A", it means something important is happening. But if there are lots of "A's", they might not know which ones are the most important. So, you start using other letters like "B" and "C" to mean other important things.

In the same way, when you use context-adaptive variable-length coding, you look at each picture and you figure out which parts are the most important. Then you come up with a special way of storing that information that makes it easier to understand the picture even when it's squeezed.

This way of squeezing and storing pictures is really smart, because it means that your friend can see the pictures quickly over the internet, but they still look good and make sense.