Gelatin is the only animal protein that is not considered a complete protein.
On the other hand, vegetable proteins (grains, legumes, nuts, seeds, and other vegetables) are incomplete proteins because they are missing, or do not have enough of, one or more of the essential amino acids. That's not such a big deal. You already know that grains and legumes are rich in complex carbohydrate and fiber. Now you learn that they can be an excellent source of protein as well; it just takes a little bit of work and know-how. By combining foods from two or more of the following columns—voilà—you create a self-made complete protein. You see, the foods in one column may be missing amino acids that are present in the foods listed in another column. When eaten in combination at the same meal (or separately throughout the day), your body receives all nine essential amino acids.
You can combine the following vegetable proteins to make complete proteins.

   Also, by adding small amounts of animal protein (meat, eggs, milk, or cheese) to any of the groups, you create a complete protein. Here are some examples: