In its simplest terms, occupational therapists help people across the lifespan participate in the things they want and need to do through the therapeutic use of everyday activities (occupations).
Common occupational therapy interventions include helping children with disabilities to participate fully in school and social situations, helping people recovering from injury to regain skills, and providing supports for older adults experiencing physical and cognitive changes.
There is this massive book OT’s use Willard & Spackman’s Occupational Therapy. I have the twelfth edition and some of this comes from that book.
To be human is to be occupational. To know what occupation is, it is necessary to examine what humans do with their time, how such activities are organized, what purposes they serve, and what they mean for individuals and society.
Personal experience of doing occupation, whether consciously attended to or not, provides a fundamental understanding of occupation–what it is, how it happens, what it means, what is good about it, and what is not.