Interior design is an evolving art and science that aims to create functional and attractive interior spaces that meet user needs. It involves understanding how people behave in spaces in order to develop conceptual plans. Interior design was once considered part of architecture but now stands on its own as a field focused on effective space use. There are various specialties within interior design like residential, commercial, healthcare, and exhibition design. To become an interior designer requires training and education in order to get a license, though some have become designers through informal apprenticeships. Designers must be creative and knowledgeable about materials, furnishings, styles and how to modify concepts over time to create unique spaces.