Explain what a relational database is and how it is structured.

A relational database (RDB) is a database management system where data is organized into tables (relations). Each table consists of rows (records) and columns (attributes).

Main characteristics of a relational database:

• Tables: data is stored in tables, where each row represents a separate object or record, and each column represents its property.
• Keys: each table has a primary key that uniquely identifies a record.
• Relations: tables can be linked to each other through foreign keys, allowing modeling of relationships between data.
• Query language: SQL (Structured Query Language) is used for working with data.

Example of a "Users" table structure:

ID (PK)	Name	Email
1	Ivan	ivan@mail.com
2	Maria	maria@mail.com

Thus, a relational database is structured as a set of interconnected tables, which ensures ease of storage, search, and data management.