What is the classification of a scale consisting entirely of half steps?

A scale consisting entirely of half steps is classified as a chromatic scale. This is because the chromatic scale is made up of twelve pitches within an octave, each a half step apart. The pattern of notes creates a rich and continuous sound, allowing musicians to explore a broad range of tonal color and mood.

In contrast, the diatonic scale consists of seven distinct pitches and follows a specific pattern of whole and half steps, while the pentatonic scale features only five notes, typically omitting some pitches for a more simplified sound. The whole tone scale consists of whole steps only, making it distinct from the chromatic scale. Therefore, the classification that fits the description of a scale consisting entirely of half steps is indeed the chromatic scale.