A complementary good or service is something used or provided in combination with another good or service. The word complementary means combining to enhance or emphasize each other's qualities.

Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

We all know that getting enough protein in our diet is beneficial to our health, but why is that? Proteins are found in every cell, tissue, and bodily fluid. It is an important component of our diet, ...