Ergonomic — adjustable to fit shape of sitter.

Gas Lift — a manual lever operation to adjust height (aka the pneumatic lift).

Task — wheeled base, with or without arms.

Executive — larger chair for executive desk.

Dual Function — 2 levers for height and seat/back adjustment.

Task Chair — a chair, with wheels and with or without arms, used for working on the computer and other such "tasks." It may be pnumatic (have a gas lift) or have a manual lift.

Guest Chair — this chair does not have wheels, may or may not have arms and may or may not be stackable. It is usually present in lobbies, waiting areas and in front of desks.

Club Chair — serving the same purpose as the guest chair, the club chair has arms and stuffed upholstery.

Managerial or executive chair — akin to the task chair, it probably has arms and may have a mid to high-back. It generally is roomier and may have more features, such as tilt or swivel.

Drafting Stool — this chair is considerably taller than others and has a foot rest.