The modern definition of a rat rod is a custom car with a deliberately worn-down, unfinished appearance, typically lacking paint, showing rust, and made from cheap or cast-off parts. These parts can include non-automotive items that have been repurposed, such as using a rifle as a gear shifter, wrenches as door handles, and old saws as sun visors. A rat rod may or may not have extraneous decorations, but will always exude a great deal of personality due to the imagination required of the builder.
An alternate, and outdated, definition of a "rat rod" is a style of hot rod or custom car that, in most cases, imitates (or exaggerates) the early hot rods of the 1940s, 1950s, and early-1960s. The style is not to be confused with the somewhat closely related "traditional" hot rod, which is an accurate re-creation or period-correct restoration of a hot rod from the same era.