Interior design is the art of applying the knowledge of interior space, with the manipulation of spatial volume and surface treatment application. Interior space design draws on aspects of environmental psychology, interior architecture design, product design and furniture design in addition to traditional decoration. An interior designer is a person who is an experienced professional in the area of interior design or one who designs interiors as part of their job requirements.

Modern Interior design is a creative practice that analyzes programmatic information, establishes a conceptual direction, refines the design direction, and produces graphic communication and construction documents.

After a design layout has been finalized, the interior designer will start specifying the materials, finishes, and furnishings required, such as furniture, lighting, flooring, wall covering, and artwork. Depending on the complexity of the design project, the designer will need to prepare drawings and submit them for architectural review which later requires approval by a construction inspector to ensure that the design is equivalent with all applicable building codes. If a design needed any structural work, the designer will need to work with an architect or engineer for that part of the project. Most designs also requires hiring of contractors to complete technical task such as lighting, electrical wiring or plumbing,. If required, the designer will select qualified contractors and write up work contracts.

Interior decoration is the art of decorating a rooms of house so that it looks attractive, easy to use, and functional well with the existing design architecture. The aim of interior decoration is to provide a unique "feel" in the room; basically it encompasses applying wallpaper, painting walls and other surfaces, choosing furniture and fittings, such as light fixtures, floorings and providing other decorations such as paintings, sculptures and carpets.