Run-length encoding

Run-length encoding is like a secret code that we can use to make long messages shorter. Imagine we have lots of pictures of a smiley face like this :-) and we want to send them to our friend. Instead of saying "smiley face, smiley face, smiley face" over and over again, we can use run-length encoding to make it shorter.

Here's how it works: we count how many times we see the same picture in a row. For example, if we see a smiley face 3 times in a row, we write "3x smiley face" instead. That means we only have to send one message instead of three.

But it gets even better! We can use run-length encoding to make all kinds of messages shorter, not just pictures. For example, if we had a message that said "aaaaaaaaabbccccccccd", we could write it as "9x a2x b8x c1x d". That's a lot shorter and takes up less space!

So that's run-length encoding in a nutshell. It helps us make long messages shorter by counting how many times we see the same thing in a row. It's like a secret code that only we and our friend understand.