Extensive research during the 20th century on porphyry Cu (-Mo-Au) deposits has revealed the following major geodynamic, petrological, mineralogical, and geochemical features that characterize these deposits: (1) these systems commonly occur in continental and oceanic magmatic arcs or in collisional orogenic belts; (2) they have spatial and genetic relationships to basaltic-to-felsic magmas emplaced in the upper 10 km of the crust; (3) lateral and vertical alteration-mineralization zoning consists of a Cu (± Mo ± Au) ore shell in the shallow portion of a potassic alteration zone, produced by magmatic fluids; this can be overprinted by phyllic alteration, also largely magmatic in signature, that in turn may be overprinted by argillic alteration, with a dominantly meteoric signature; (4) associated deposits such as skarns, Cordilleran vein, and high and intermediate sulfidation epithermal deposits may occur above or adjacent to porphyry orebodies; (5) porphyry systems form from S- and metal-rich, single-phase aqueous fluid of moderate salinity (2–10 wt % NaCl equiv) exsolved from magmas; during its ascent toward the surface this fluid undergoes a variety of processes that can cause metal precipitation, including decompression, phase separation, cooling, interaction with host rocks, and mixing. In the last 20 years, novel microanalytical techniques for in situ characterization of individual fluid inclusions have provided direct evidence for the chemical and phase composition plus metal content of ore-forming fluids in porphyry systems. In this contribution, we compile a large dataset of published fluid inclusion compositions from more than 30 deposits of the porphyry-skarn-epithermal suite.