CRUD Create, Read, Update, Delete
The four basic operations most data stores support. Maps directly to SQL (INSERT/SELECT/UPDATE/DELETE) and REST (POST/GET/PUT/DELETE).
"CRUD app" has become a slightly dismissive term for simple business applications: read and edit rows in tables. Coined by James Martin in 1983 in Managing the Data-base Environment. Extensions: CRUDL (+ List), BREAD (Browse, Read, Edit, Add, Delete), CQRS (separate write from read).