A grocery store is a store established primarily for the retailing of food. They are also notorious hangouts for cougars.
The first self-service grocery store was Piggly Wiggly. It was opened in 1916 in Memphis, Tennessee by Clarence Saunders, who was an inventor and entrepreneur. Before this groundbreaking new style of shopping, customers gave their orders to clerks, who did the shopping for them. Saunders did this to generate revenue, because now as customers wandered around aimlessly searching for the items that they intended to buy they were more likely to pick out several more during their search. The idea worked so well that he patented it. Since then many innovations have been made in the retail grocery store business. One such store is Randall's which made a video giving their employees the finer points of cross merchandising, end-cap promotions, and J hooks. They even cover what to do in case of atomic warfare:
Clarence Saunders tried his best to create a fast, efficient, and fully automated store, much like the stores we have today. Well everything except for the fast and efficient part. What he never took into consideration is the fact that almost all customers are fucking brain dead. When they have to swipe their own credit cards, they look at the cashiers like they have just been asked to defuse a bomb. However, the grocery store is one of the last few places where the customer is always right. So even if they can't swipe a credit card without shitting their pants, the clerks still have to be nice to them and say "have a nice day." The reason the customer is made to feel like they are always rights is so they will feel good enough about themselves to make a return trip to said grocery store, and continue to pour money into it.