What is a relation (relationship) in the context of databases?

In the context of databases, a relation (or table) is a mathematical concept that underlies the relational data model. A relation is represented as a table consisting of rows and columns, where:

• Rows (tuples) are individual data records.
• Columns (attributes) are fields with specific data types.

Each relation has a unique primary key — a column or set of columns that uniquely identifies each row. Relationships between tables are implemented through foreign keys, which reference primary keys of other tables.

Example of a relation "Users":

user_id (PK)	name	email
1	Ivan	ivan@mail.com
2	Maria	maria@mail.com

Here, user_id is the primary key, uniquely identifying each user.

Thus, a relation is a table with a defined structure that allows storing and linking data in a database.