Especially "pop", which can also be understood as the adjective "popular" according to the context.

- it comes from rock'n roll, which at first was basically blues with a faster tempo.

- it oftens features the use of guitar(s), electric bass, drums

- it's nicely raw, maybe even nasty

- important rythm section

- it is a hybrid type of music. If you listen to stuff like Andy Williams, it is pop(ular) music, that came from folklore influences I believe.

To me, the Beatles and the Beach Boys were one of the most important acts in the genesis of modern pop music, even if they actually started by playing rock'n roll (the Beatles), and gradually loosen the structure. World music, folk, soul, swing, jazz, traditionnal pop music were important influences as well.

- for the instrumentation, it's way wider than rock. Strings, acoustic guitars, drums, electric bass, keyboards/piano/synths.

- important melodic section.

The two genres are kind of a crossroad of music influences, or at least they go well together, hence the label "pop/rock".

When rock'n roll appeared in the 1950s, it was already mixing with pop music in some occasions. Roy Orbison's ballads are, to me, a nice mixture of rock'n roll and pop sound.

Some bands were still doing old school rock'n roll/blues, but in a new way, and it gave birth to new types of rock. For instance, Led Zeppelin, with huge blues influences, created the foundations for hard rock to grow on.

Let's take a band like Foals, for instance. Is it pop ? Is it rock ? It has features from both of those styles. Some will use subgenres to describe it (in the Foals' case : math-rock), some will describe it rock, some will go for pop-rock.

Some people listen to The Kills for their electronic beat, some for the heavy guitar. I like to listen to them as it was heavy blues.

In the late 19th century Americans started used the term popular music, as opposed to classical music, for songs that appealed to a big audience: sheet music, dance hall music, Tin Pan Alley. They were tunes that people could easily remember and sing along.

In 1951 disc jockey Alan Freed used the term rock and roll to describe the new style of popular music that would gain worldwide popularity by being played on the radio, in jukeboxes and in dance venues in the fifties. A rock and roll band typically had a lead guitar, a rhythm guitar, a bass guitar or double bass and drums; sometimes also piano.

In the mid-fifties the British media started describing the music in the singles charts as pop music. That included rock and roll songs, but also popular songs with big band etc.

From the late sixties on people sometimes started distinguishing between pop and rock music. There is no clear borderline. "Pop" was used for music that was oriented towards the singles charts. "Rock" was used for music that was played on rock concerts or festivals like Woodstock.

Since the late seventies "pop" is used more often for songs with an electronic sound and dance rhythms. "Rock" is usually with electric guitars, bass guitar and drums, but acoustic rock exists too.

Pop changes every decade. In the late seventies disco was dominating the charts. When one says "eighties pop" he's probably referring to the synth pop bands of that era.

"Pop" in the narrow sense, or mainstream pop, can have the negative connotation of being produced for purely commercial purposes. "Rock" is more associated with antiauthoritarian youth culture. However this labeling of music as "commercial" vs. "authentic/rebellious" can be very subjective. A band with a rock sound can get major media exposure and sell millions of records. A singer with a pop sound can sing a ballad that comes straight from the heart. Then who is commercial and who is authentic?

In the wider sense "pop(ular) music" can still be used for one of the four major kinds of music, next to classical, jazz and world music. In this broader meaning pop music includes genres like rock, mainstream pop, electronic dance music, R&B and hip hop.

To identify rock music or pop music you'll need to listen a good amount of songs from different genres first.

• I will define ROCK music as music with a lot of electric guitar/acoustic guitar or in a few cases pianos and now cellos too! and most of the voicals have a heavy manly voice, also female do rock music like Hayley Williams of ‘Paramore’, it's hard to accurately categorise them as there are a whole lot of sub-genres like punk rock, emo-rock, goth-rock, grunge-rock, metal, alternative rock, progressive rock and a lot more.
• Wikipedia says, Rock music is a broad genre of popular music that originated as "rock and roll" in the United States in the early 1950s, and developed into a range of different styles in the 1960s and later, particularly in the United Kingdom and in the United States. It has its roots in 1940s and 1950s rock and roll, a style which drew heavily on the African-American genres of blues and rhythm and blues, and from country music.
• Some rock artists/bands - Led Zeppelin, Queen, Metallica, AC/DC,Coldplay, Green Day (punk rock), Stained, Sum 41, Linkin Park, Paramore, Evanescence and a lot more.

And I should mention it here as there exists a genre that is Pop-Rock.

But I'll write what is pop music first,

• The word pop first comes from the word popular, pop music means ‘widely accepted’ because of it catchyness, the message or advertisement or its reach to the mass. Its always very popular because of the fact that it has been advertised a lot and the singers of the songs are mostly pop icons such as, Michael Jackson, Justin Bieber, Madonna, Britney Spears. Pop music is the most widely played music in the world.

What are some other characteristics of pop songs?

• Song that is from a different genre also comes into the category of pop (for example Avicii's Wake me up come from EDM from because of its pop elements and also the popularity, it's a pop song or electronic-pop song),
• Pop songs have a hook, either a melodic hook or a vocal hook which is very catchy to listen, pop songs can be songs that entered the genre from a different genre because of the popularity (as mentioned above) and its wide acceptance (so now you know what pop-rock is). The main elements of a pop songs now are that the instruments you listen in the songs are synths and electric elements, they also make pop music with a lot of piano, guitars, electric guitars, drums (of course), violins, cellos and any other instruments
• Pop genre/artists tends to adapt any other genre that is gaining popularity, for example, we are hearing a lot of pop music with house music elements and dusted element or I should say EDM (Electronic dance music) in general. Some EDM pop artists are, Avicii, Skrillex, Calvin Harris and others.
• Some pop music artists - Michael Jackson, Madonna, Lionel Richie, Justin Bieber and others

P.S. - You should also check what pop culture is.

Source: my craziness about music.

Edit: a minimal/funny explanation.

Warning - A little NSFW/Non-Christian (don't judge me) content ahead -

Rock music makes instrumentalists famous but Pop raises the vocalists.

1. Melisma Melisma melisma
2. Big sing along choruses
3. Simple melodies
4. Huge tonal spreads from sub bass to high treble
5. Easily shuffled parts for endorsement and potential remixing
6. Good looking youngsters "feeling it" on stage
7. No consistent story to tell or perspective
8. Massive commercial and corporate support
9. A general manufactured sheen
10. Legions of young inexperienced fans

To be fair - Fun is simply bad pop, but songs like "uptown shuffle" (Bruno Mars?) use all the same tricks to make something that's legitimately fun. No pun intended.

Pop, just to clarify was originally a term applied to all music that was popular or on popular radio. Generally we see 'pop' music as starting from about the start of the 1900s to the present day.

However, during the 50s-present day, as more genres became apparent, pop started to be used to describe a specific 'sound' attributed to certain music or bands. It is generally given to music that sounds 'generic' like the majority of current music.

In music history, we use the term to describe ALL popular music including all the genres from Jazz, country, rock, hip-hop, dance etc.

The modern day 'pop' 'genre' is typified by very mild/generic sounding drumbeats and instrumentation and usually sticks to common chord progressions that people are familiar with. Pop music is literally the most generic form of music designed to be tame so that anyone can like it.

Pop music generally utilises influences from all genres, unlike rock which tends to stay to it's own genre.

Rock on the other hand, has a more powerful feel to it. Rock is a form of popular music, especially true for the 60s-80s and is an umbrella term for different sub-genres of rock. Subgenera may include, stadium rock, soft rock, glam rock, folk rock etc.