A modular kitchen is one that is made up of pre-made cabinet parts. These parts are fitted together to create a whole, functional kitchen design. Modular cabinets are popular in kitchen remodeling projects and are available in two main types: upper and lower units. There are also full units such as closets or pantries that fit from floor to ceiling. Since a modular kitchen is pre-made and purchased ready made in sections, often flat packed for home assembly, it's the opposite of a custom made kitchen that is built on site.