A rich client is like having a really cool toy that can do a lot of fun things. Imagine that you have a really awesome toy car that has a lot of buttons and switches that make it do cool stuff. That car is like a rich client.
When you use a rich client, it means that you can do a lot of things on your computer without needing to be connected to the internet. It's like having all the cool features of a website, but on your own computer.
For example, if you wanted to play a game or use a program that had a lot of fancy graphics and cool animations, you could do that with a rich client. This is because the program is stored on your own computer, so it can use all the power of your computer to do things like show beautiful pictures or make fun sounds.
So, when people talk about a rich client, they are really talking about a fancy program or application that you can use on your computer that doesn't need the internet to work. It's like having your own little toy that can do amazing things without having to share it with anyone else.