You might've heard of cafes and coffee products referred to as "waves" ... most usually, "third wave" as a descriptor for coffee or cafes.
"Waves" are how coffee historian Timothy Castle described the growth of "craft" coffee in North America, and the term caught on.
First wave occurred ~1900 and describes the adoption of coffee into the American lifestyle en-masse. This is Folgers' era, the time when everyone served Folgers and everyone else claimed to. Coffee wasn't good, wasn't even really particularly differentiated, and generally awful by modern standards. But they didn't care - drinking coffee was American, and if that was what coffee was like, they'd enjoy it that way.
Second wave is the era of Starbucks', but started long before Starbucks did, in the 1960s or so when substantial brand differentiation entered the domestic market and "going out for coffee" was adopted into culture just as ubiquitously as coffee itself was 60 or so years prior. The rise of the cafe brought into style "Italian-style" coffees, and thus the espresso bar, the chain cafe ... Coffee was recognized as having quality and taste differences, and the public developed preferences.
Third wave is ... now, plus probably another 30 or so years. Coffee as an artisanal luxury product, something bearing consideration similar to wine, or existing in a culture of connoisseurship. People are exploring and developing the "craft" associated, the over the top people have way over the top ways to explore their fascination; the average consumer has clear and well-understood preferences that span multiple brands, and has the awareness to select something they believe they will like from a range of unfamiliar brands.
But put simply, the three waves are just the labels for each era in the fairly easily trisected history of coffee in North America.