Since ancient times there have been two types of cultures in the west: the official culture, the culture of the ruling class, which includes literature and philosophy and great works of art; and many local cultures which include songs, stories, and crafts.
Everything changed with the rise of factories. It became possible to cheaply make many identical copies of objects; not only clothing and household items, but also cultural works such as books and newspapers, and later: radios, TVs, music players, and video players. Alongside the official culture and the local cultures, an entirely new category of cultural work arose: mass culture.
Mass culture is different from both the official culture and from local cultures in several ways:
Transmission is fast, wide and easy: Transmission of cultural works doesn’t require long study, or apprenticeship, or prolonged person-to-person contact. Cultural works can be rapidly and easily transmitted to many people of all walks of life and over a wide geographical area.
It comes from outside: The official culture is created by members of the elite and is mostly aimed towards other members of the elite. Similarly, local cultural works such as crafts and folk music are created by and for members of a particular group or a particular community. Mass culture is different in that the people who create it have little in common with the majority of the people who consume it.
Commercial: Works of the official culture were (in the past, at least) created by people who had no need to earn a living. The purpose of their literature, philosophical treatices, and works of art was to explain the world, to find beauty or enlightenment, to gain prestige, to create a sense of identity or meaning, or simply to pass the time. The songs, stories, and artworks of local cultures were very different from those of the official culture, but they served a similar set of purposes; they told people who they were and how they should live, and they provided beauty, meaning and entertainment. Mass culture is very different; the driving force behind it is a commercial drive for profit. The cultural works don’t matter in and of themselves, what matters is how many copies of the cultural work can be sold, or (more often) how well the cultural work functions as a delivery mechanism for advertisements.