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.

In the business world, you may bill a client more than once during or after a billing period for additional expenses incurred due to additional products or services. The new bill you send is a ...

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, ...