What makes a great guitar riff?

Even amidst today's giant musical melting pot, the ingredients for creating a memorable guitar hook remanin relatively simple. In essence, there are two categories of riffs. First, there's the kind that exhibit a catchy melodic or chordal sequence (for example,"Stairway to Heaven"). then, we have the type that employs a notable rhythmic cadence (for example,"Smoke on the Water"). Tone, performance, and other cosmetic fixing are simply creative honus points to the core idea, much like a great guitar solo is just a premium within an excellent song.