A relative says that carbon-14 dating of human fossils is flawed. How are fossils dated?

Science is the backbone of my beliefs, but my relative says that carbon-14 dating is flawed. What is the gist of the carbon-14 dating technique? I'm already familiar with the nuclear interactions that cause carbon-14 to be radioactive. I'm more interested in the actual dating process and what the 'thing' is that is dated in fossil imprints, for example.