Countertop usually refers to a horizontal worksurface in kitchen

Kitchen

A kitchen is a room or part of a room used for cooking and food preparation.In the West, a modern residential kitchen is typically equipped with a stove, a sink with hot and cold running water, a refrigerator and kitchen cabinets arranged according to a modular design. Many households have a...

s or other food preparation areas, bathroom

Bathroom

A bathroom is a room for bathing in containing a bathtub and/or a shower and optionally a toilet, a sink/hand basin/wash basin and possibly also a bidet....

s or lavatories, and workrooms in general. It is frequently installed upon and supported by cabinet

Cabinet (furniture)

A cabinet is usually a box-shaped piece of furniture with doors or drawers for storing miscellaneous items. Some cabinets stand alone while others are built into a wall or are attached to it like a medicine cabinet. Cabinets are typically made of wood or, now increasingly, of synthetic...

s. The surface is positioned at an ergonomic height for the user and the particular task for which it is designed. A countertop may be constructed of various materials, both natural and manmade, each with its particular attributes with respect to functionality, durability, and aesthetics and may incorporate or house appliances or accessory items relative to the intended application.
The common fitted Western kitchen

Kitchen

A kitchen is a room or part of a room used for cooking and food preparation.In the West, a modern residential kitchen is typically equipped with a stove, a sink with hot and cold running water, a refrigerator and kitchen cabinets arranged according to a modular design. Many households have a...

, developed in the early 20th century, is typically an arrangement of assembled unit cabinetry covered with a more-or-less continuous countertop work surface.