A sliding window as the name suggests has sliding sash. The operable sash operates on one plane while the fixed sash is fixed on another plane. You could also have a configuration where all sash slide on different planes. When the operable sash slide horizontally it is a horizontal sliding window. If the operable sash slide vertically then they are referred to as called Single or Double Hungs.
Sliding windows come prefit in frames with hardware installed. All sash are machined for necessary hardware like rollers and balances, and tested. Weatherstripping is included where necessary. Frames come with a sloped sill. Exterior moulding is applied if requested. A screen with aluminum surround is also supplied on a typical crank out casement. A wood screen is an option.