deciding nonnegativity of real polynomials is a key question in real algebraic geometry with crucial importance in polynomial optimization. it is well-known that in general this problem is np-hard, therefore one is interested in finding sufficient conditions (certificates) for nonnegativity, which are easier to check. since the 19th century, sums of squares (sos) are a standard certificate for nonnegativity, which can be detected by using semidefinite programming (sdp). this sos/sdp approach, however, has some issues, especially in practice if the problem has many variables or high degree. in this talk i will introduce sums of nonnegative circuit polynomials (sonc). sonc polynomials are certain sparse polynomials having a special structure in terms of their newton polytopes and supports and serve as a nonnegativity certificate for real polynomials, which is independent of sums of squares. i will present some structural results of sonc polynomials and i will provide an overview about polynomial optimization via sonc polynomials.