Which air fittings should I use?

I went to the store to buy fittings for my compressor and brad nailer but was confronted with a dizzying array of types. What's the difference between automotive, industrial, and universal air fittings? Which should I use?
—Glen Ramey, Yuba City, Calif.

Quick-connect air couplers look similar, but they come in at least 10 different styles that often don't play well together, Glen. Further confusing matters, some styles carry multiple names; for example, automotive, T-style, and Tru-Flate all refer to the same fitting. Fortunately, a universal coupler (the female socket) will usually accept the two most popular male fittings, industrial and automotive, commonly available in home centers and hardware stores.

In the end, the choice boils down to personal preference, or even your best guess. One hint: If your workplace or the buddy you borrow tools from uses a particular style, that's as compelling a factor as any as to which you should choose. Whichever you go with, make sure you have all your tools similarly equipped.