Interior designers create indoor spaces that satisfy the client's need for aesthetics, safety and function. Through the use of furniture placement, colour palettes, decorations and functional decor, designers create kitchens that are beautiful yet functional and theatre entrances that convey the excitement of a blockbuster film while ensuring crowd safety. Elements such as artwork, lighting, window treatments and flooring must work together to contribute to an overall look that will satisfy the client's needs.

Designers may specialize in commercial or residential design or be involved in both. Two new and emerging areas of interior design are green design and ergonomic design. In ergonomic design, designers work to create spaces, especially work environments, that contribute to good posture for employees confined to offices for most of the day. For labourers, designers create spaces and work areas that will result in reduced muscle strain. Green design incorporates the use of renewable, recycled or energy-efficient elements to create a more environmentally friendly space.