A parabolic arch is a special type of arch that is shaped like a valley between two mountains.
Imagine you are drawing a rainbow in the sky, but instead of it being curved just at the top, it is curved all the way down to the ground. This is what a parabolic arch looks like, and it is used in many buildings and structures because it is very strong.
When you push on a parabolic arch, the weight is spread out evenly all the way along the arch, so it can support a lot of weight without breaking. It is kind of like when you push on a see-saw in the middle, and you and your friend stay balanced because the weight is spread out evenly on both sides.
Parabolic arches have been used in buildings for a very long time, because they are not only strong and stable, but they are also very beautiful to look at. Many famous buildings, like the Gateway Arch in St. Louis, Missouri, and the Sydney Opera House in Australia, use parabolic arches in their design.