A classic
diner is a
restaurant shaped like a
railroad dining car (the source of the design), usually having a counter with fixed, swivelling seats in front of it and a grill behind it where a
short order cook is cranking out the
pancakes,
burgers and
eggs over easy. There may or may not be an aisle separating the counter from any additional booth seating in the front of the long, narrow room.
Edward Hopper was a big fan of diners.
There were many companies that manufactured such diners in the first half of the twentieth century (most diners have a small nameplate somewhere in the interior identifying the company that built it, but they are often small hard to find), but one of the most well-known is Worcester Lunch Car Company, based in Worcester, Massachusetts. Diner fanatics consider Worcester diners to be the best examples of the genre, with superior craftsmanship that included marble countertops and lots of fancy stainless steel detailing.
There are lots of good examples of Worcester diners still in use, including the Miss Worcester Diner and the Boulevard Diner, both in Worcester, the Miss Bellows Falls Diner in Bellows Falls, VT, and the Miss Portland Diner in Portland, ME. I haven't been able to find any information about why so many of the Worcester diners are called "Miss."