A wheelchair is a mobilized form of chair using two or more wheels, a footrest, and an armrest usually cushioned. It is used when walking is difficult or impossible to do due to illnesses, injury, disabilities, or age-related health conditions. Wheelchairs provide mobility, postural support, and freedom to those who cannot walk or have difficulty walking, enabling them to move around, participate in everyday activities, and live life on their own terms.

Wheelchairs come in a wide variety of formats to meet the specific needs of their users. They may include specialized seating adaptions, and individualized controls, and may be specific to particular activities, as with sports wheelchairs and beach wheelchairs. The most widely recognized distinction is between motorized wheelchairs, where propulsion is provided by batteries and electric motors, and manual wheelchairs, where the propulsive force is provided either by the wheelchair user or occupant pushing the wheelchair by hand (self-propelled), by someone else pushing from the rear using the handle(s), or pushing from the side using a handle attachment.

The Sanskrit grammarian Pāṇini (circa 5th century BCE India) mentions the Sanskrit word parpa for wheelchair in his Aṣṭādhyāyī 4.4.10.

The earliest records of wheeled furniture are an inscription found on a stone slate in China and a child's bed depicted in a frieze on a Greek vase, both dating between the 6th and 5th century BC. The first records of wheeled seats being used for transporting disabled people date to three centuries later in China; the Chinese used early wheelbarrows to move people as well as heavy objects. A distinction between the two functions was not made for another several hundred years, until around AD 525, when images of wheeled chairs made specifically to carry people began to occur in Chinese art.

Although Europeans eventually developed a similar design, this method of transportation did not exist until 1595 when an unknown inventor from Spain built one for King Phillip II. Although it was an elaborate chair having both armrests and leg rests, the design still had shortcomings since it did not feature an efficient propulsion mechanism and thus required assistance to propel it. This makes the design more comparable to a modern-day highchair or portable throne for the wealthy than to a modern-day wheelchair for disabled people.

In 1655, Stephan Farffler, a 22-year-old paraplegic watchmaker, built the world's first self-propelling chair on a three-wheel chassis using a system of cranks and cogwheels. However, the device resembled a handcycle more than a wheelchair since the design included hand cranks mounted at the front wheel.

A self-propelled wheelchair was made for the Parliamentarian commander-in-chief Sir Thomas Fairfax due to the many injuries he had received during the English Civil War, and he used it during the final years of his life. The wheelchair of Thomas Fairfax is currently on display at the National Civil War Centre in Newark-on-Trent.

The invalid carriage or Bath chair brought the technology into more common use from around 1760.