I find pop music fascinating but have trouble understanding what is actually considered pop music.
Its a type of genre. its really popular in the us and uk through the 1950s
Oh wow that far back? 
oh yea. pop music is known to be popular music also. they are usually used interchangeably.
I never realized that. Im sure its a big market?
zydeco, klezmer and slack-key.
Distinctive styles of American popular music emerged early in the 19th century, and in the 20th century the American music industry developed a series of new forms of music, using elements of blues and other genres of American folk music. These popular styles included country, R&B, jazz and rock. The 1960s and 1970s saw a number of important changes in American popular music, including the development of a number of new styles, such as heavy metal, punk, soul, and hip
Pop music
Pop music is a genre of popular music that originated in its modern form in the United States and United Kingdom during the mid-1950s. The terms "popular music" and "pop music" are often used interchangeably, although the former describes all music that is popular and includes many diverse styles. "Pop" and "rock" were roughly synonymous terms until the late 1960s, when they became increasingly differentiated from each other.
Although much of the music that appears on record charts is seen as pop music