Interior design is a discipline that looks after designing all of the interiors of a space. This can include things like flooring, windows, doors, walls, lighting, furniture, and miscellaneous design pieces. The goal of interior design is generally to make a space that is both comfortable and aesthetically pleasing, often catered specifically to the needs and likes of the person hiring the interior designer. Interior design is actually a relatively old discipline, although historically it was reserved primarily for royalty and the aristocracy. In the modern world, many people make use of interior design, either doing it themselves with the assistance of classes or books, or by hiring an interior designer to assist them in bringing their vision to life.

The work of a designer can range from laying out small dwellings, to designing massive corporate buildings, to coming up with a cohesive aesthetic that will be used in many businesses under a single umbrella, such as the design of an international hotel chain. The best practitioners of interior design use a wide range of different skills in their work, melding bits of architecture, psychology, aesthetics, and product design to create a cohesive whole. They must also have a grasp of many fields that are important to their work, including things like how floor plans work, and what local building codes might limit their design decisions.

Most interior designers choose a specialty to focus on, as this allows them to become well versed in the diverse skills needed to do their job. For example, someone who designs airports is likely to work primarily on airports or similar structures, as a great deal of time must be invested in becoming familiar with the requirements of airports, and most of this knowledge would not be transmittable to, for example, a loft apartment. More broadly, an interior designer may choose to focus on commercial design, which would encompass a diverse range of buildings, like schools, hospitals, and government buildings, or may choose to focus on residential spaces.

In recent years, some interior design has adopted many of the tenets of sustainable building, trying to design spaces that are functional, aesthetically pleasing, and sustainable. Designers who choose to pursue this particular area of interior design often become accredited by taking the Leadership in Energy and Environmental Design (LEED) examination. There is a large market for LEED-certified designers currently, as more and more businesses choose to attempt to become LEED-certified in their spaces, as this is seen by consumers as a sign that the company takes their environmental impact seriously.

Although many interior designers work on a contract basis, a number are actually kept on as full-time staff. Independent designers generally take on smaller clients, and help them with a specific project or set of projects, building a quote, working with the client to determine what would best suit them, and then working with builders or suppliers to realize that vision. Larger corporations, on the other hand, may find it cost-effective to simply keep an interior designer or team of designers on staff. This is particularly true of companies that need to keep a strong brand design in many buildings.