Proteins are a very important kind of molecule for living organisms. They are a component of many kinds of organic tissue, and they are important in the running of many biological processes (for example, enzymes are a kind of protein).
Proteins are complex molecules made up of chains of simpler amino acids. There are a limited number of amino acids which combine in multifarious ways to form a great variety of proteins. All of them are made of four main elements—carbon, hydrogen, oxygen and nitrogen—and occasional other elements.
Proteins are a vital constituent of any human's diet. Meat, fish, eggs, cheese and pulses (such as beans) are all good sources of protein. The majority of foods that are rich in protein are derived from animals, which is why vegetarians and particularly vegans need to be careful to make sure they get enough protein, often done by eating a great volume and variety (to get the variety of amino acids needed) of beans and nuts. Soy beans are a particularly prized source of protein among vegans.
At the other end of the spectrum, people wanting to build a lot of muscle such as bodybuilders and professional wrestlers may ingest copious quantities of protein-rich food, like egg whites and chicken breasts, or specially-prepared food such as protein drinks.
We often say that DNA contains the blueprint for life, but more specifically, it actually contains the instructions for making proteins in a particular way inside cells. Therefore, protein manufacture can be said to be the fundamental connection between life's blueprint and life itself.