Top-shelf liquor

A well drink or rail drink is an alcoholic beverage served using the lower-cost liquors stored within easy reach of the bartender in the counter 'speed rail' or well. Well drinks differ from "call" drinks in that the former are offered when a customer does not specify a particular brand of liquor when ordering a mixed drink. The terms "well drink" and "rail drink" come from the name for a bartender's workspace, known as either the well or the rail. In any given establishment, the rail/well liquors available may be known as the "house pours" or "house brands".

The actual liquors used by a drinking establishment will vary. A bartender's well may include at least one variety of gin, rum, whiskey, vodka, bourbon, tequila, triple sec, and vermouth.

Some establishments that cater to higher-end clientele or wish to project an aura of luxury choose premium brands to be their well liquors (thus offering a "premium well").

A rail or well drink is usually served when a customer does not specify that a particular brand of liquor be used. For example, a customer order for a "Scotch and soda" would lead the bartender to use a rail/well Scotch whisky and would be priced as a well drink, whereas ordering "Glenfiddich and soda" would be a call drink.

Call liquors are known as such because the customer "calls" or requests a particular brand of liquor.

Certain expensive brand-name liquors are not considered or priced as call, but are instead known as "top-shelf" liquors, both from their placement on the shelves and from their price relative to the other liquors available.

Common well drinks can include cocktails and highballs like:

...
Wikipedia