[wutbrodo]

It's not a traditional genre as much as a characterization, but it definitely has hallmarks that you can identify without reference to its popularity. From Wikipedia:

> Identifying factors usually include repeated choruses and hooks, short to medium-length songs written in a basic format (often the verse-chorus structure), and rhythms or tempos that can be easily danced to.

BTW, Wikipedia also draws a distinction between "pop music" and "popular music", where the latter is defined as you describe.

[thereddaikon]

That definition is so broad as to include almost all modern western music. Such a loose definition doesn't serve much a purpose as a genre.

[oneoff786]

Define rock

[thereddaikon]

Roots in blues, and its composition is based on blues paradigms like the pentatonic scale and writing structure, 4/4 or 3/4 time signature. Instrumentation has but is not limited to, at least one electric guitar, bass, drum kit and a vocalist. Song structure will usually adhere to a verse chorus verse chorus bridge trope.