This chapter presents a general overview of the major controls of trace metals in seawater, developed from the extensive research on trace metals over the last few decades. The reader should be given a first-order understanding and insight into trace metal biogeochemistry in the oceans, rather than presented with a comprehensive review of the distribution of each trace metal. Each of the trace metals discussed will undoubtedly prove to have unique characteristics and subtle differences from this version, yet the comparison with these characteristics will serve as a good springboard to a more complete understanding.