A while back, a friend of mine sent me a message suggesting that I write a clear explanation of the objective characteristics of different genres as well as give my subjective opinion on each and how I derive that opinion.  I have created a new category of posts as a response to that request.
Genres are tricky. First of all, the characteristics of genres overlap with those of other contemporary genres. It can be difficult to separate R&B and hip-hop, EDM and dubstep, swing and big band, and so on. Second, genres don’t suddenly appear. They develop and morph over time until one day the world realizes that there’s a new species of music. Look at rock. Elvis’s rock ‘n’ roll is different from The Who’s rock, The Who is different from Metallica, and Metallica is different from Disturbed. Third, music can rarely be labeled as just one genre. For instance, if you look up Gorillaz’s genre on Wikipedia you’ll see pop, Britpop, hip hop, alternative hip hop, trip hop, rap rock, alternative rock, indie, dub, reggae, and electronica. Finally, genres can be broken down into sub genres that can seem entirely different from other sub genres in the same genre.
As such, I cannot give a description of every genre. I couldn’t even list all of them. I plan to cover a few of the main genres: classical, jazz, country, rock, pop, hip-hop, and electronic. I’ll also explore some of their sub genres.
There are two ways to try and distinguish genres: quantitative and qualitative measures. Quantitative measures include the kind of instruments used, rhythm, cadences and chords, EQ, dubbing, use of samples, etc. This is the kind of stuff Pandora looks at when it makes your radio station. Qualitative measures deal with content and the soul of the genre. This is mainly what I will be exploring in future posts when I cover particular genres.
Keep this in mind: I do not hold one genre to be better than another.  I think that some individual songs and artists are better than others, but typically I will compare these within the same genre. I like some genres better than others, but this is a matter of taste. I will do my best to make clear what is my taste and what I believe to be objective characteristics.