Proteins are large molecules consisting of 20 individual components called amino acids. Humans need to eat proteins because some of the components are very important and almost everything in the body is made of proteins.
Proteins are formed by putting the individual building blocks together in a long chain, like a string of pearls. The order is fixed in our genes so that just the right beads are added one after the other. This chain then winds up into a thick ball. Only in this way the protein can work properly in the body and find its place.
Important tasks of proteins in the body are holding everything together and stabilizing it. They do a lot of small jobs that only a certain protein can do, because it has the right form and thus the key to solve the task. Proteins in the body are also there for safety and health. When bad substances come, they catch them so that we don't get sick.