What characterizes the '12-bar blues' form?

The 12-bar blues form is characterized by a repetitive chord progression that spans over 12 measures, creating a distinctive and recognizable musical structure. This format typically involves a specific chord sequence, often expressed as I-IV-V, which defines the harmonic backbone of blues music. The repetition within these 12 bars allows for variations in melody and lyrics, making it ideal for improvisation and expression. This structure is foundational in many jazz, rock, and rhythm and blues genres, providing a familiar framework for musicians and songwriters to explore.

The other options do not accurately describe the characteristics of the 12-bar blues. For example, the notion of unique instruments is not relevant to the form itself, as it can be played with various instruments. The structure of 12 verses with no chorus misrepresents the way blues songs are typically built, as many incorporate distinct verses and choruses. Lastly, while the tempo can vary, the defining feature of the 12-bar blues is not inherently a fast tempo or high energy but rather the chord progression itself.