A fisheye lens is a special type of camera lens that has a really wide view. When you look through a regular camera lens, you only see a small part of what's in front of you. But with a fisheye lens, you can see almost everything around you! It's like looking through a big peephole.
The reason why it's called a "fisheye" lens is because the images it produces can look like what you'd see if you were a fish swimming underwater and looking up at the sky. The sky would look like a big dome, and everything around you would be stretched and curved.
Fisheye lenses are often used by photographers who want to capture really dramatic, unusual images. They can also be used to show a whole room or landscape in one shot, without having to stand really far away.
But there are some things to keep in mind when using a fisheye lens. Because the lens is so wide, it can distort objects and make them look skewed or curved. People might look like they're in a funhouse mirror! So it's important to use the lens carefully and considerately.