Hats on a raspberry pi are pieces on extra tech that you can connect via the GPIO pins. There are a bunch on different types of hats that are popular. The first is the sense hat. It has a couple rows of pixel LEDs and a temperature, humidity, gyroscope, and a bunch on other things as well.

You can code and use a sense hat several different ways. You can use scratch, python, vscode, and a bunch of others.

There is also the unicorn Hat. This is more focused on the LEDs and lights.

When turned on it looks just like the sense hat. Then there is the build hat.

The build hat allows you to add up to four different sensors and motors on to your raspberry pi.

If you are just starting out and are wondering what hat to buy first, I would suggest the sense hat. It has the most capabilities and one of the easiest to inquire.You can buy it for $34.19 from the pihut or from amazon for $34.70. But wait! What if you have a Raspberry pi 400? How to you use hats? The answer is the pimoroni ribbon extension cable or any cable you can find on amazon. Before you buy make sure that It is compatible with your pi.