Schema
also: schemas, database schema, data model
The blueprint of your database: which tables exist, what each one stores, and the rules that data must follow.
The formal definition of a database's structure: its tables, columns, data types, keys, constraints and relationships. Changing it usually requires a migration so existing data fits the new shape.
The printed layout of a paper form: which boxes exist, what goes in each, and which are required. The filled-in forms are the data. The layout is the schema.
When your agent adds a feature, it often changes the schema too. Schema changes affect every existing piece of data, so they deserve more care than a normal code edit.
I've updated the schema to add a cooking_time_minutes column to recipes. I'll generate a migration so your existing database picks it up.
Before writing any code, show me the current schema for bookings and customers. Explain what you'd change and why.
Thinking the schema is the data itself. The schema is the shape and the rules. The data is what's stored inside that shape.