We've all used a phonetic alphabet, even if we didn't realize it at the time. Whether you were on the phone with the dentist's office or the cable company, you've probably used a version of one to make sure your name is spelled correctly. "It's Sam," you shout into the receiver. "S as in salamander, A as in Adam, M as in mouse." Maybe you just pluck words from the sky — anything to prevent 'Sam' from becoming 'Fan' or 'Ham' for the umpteenth time.
For the servicemen and women who first used spelling alphabets back in the early 1900s, however, the difference between "M as in metro" and "C as in coca" was a life or death distinction. Imagine you're on the radio, trying to warn soldiers of a mustard gas attack. You'd want to make sure they heard "mustard," not "custard."
Welcome to the NATO alphabet.