Rockabilly is a type of music best described as early American rock and roll. Pioneers of the genre include Elvis Presley, Gene Vincent, Eddie Cochran, and Buddy Holly.
There have been several little rockabilly revivals, but nothing compared to the swing revival. In the early/mid eighties there were the Stray Cats and The Cramps and in the late 90s The Reverend Horton Heat.
There are several subgenres of rockabilly including: psychobilly, voodoobilly, country swing, and neo rockabilly. If you are not sure a band could even be considered rockabilly, you can call it probabilly.