What is a database?

A college portal needs to remember students, courses, and enrollments. A shopping app needs products, orders, and delivery details. These applications need more than a temporary variable: they need information that can be stored, found, updated, and used consistently. A database is a system designed to manage that information.

Data needs structure and rules

In a relational database, information is commonly organized into tables. A Students table might contain one row per student, while a Courses table contains one row per course. Each row represents a record, and columns describe properties such as a name or course code. A unique identifier helps distinguish one record from another.

Tables can be connected. An Enrollments table might link a student identifier to a course identifier. This avoids repeating all the student's details every time they enroll in a new course. The database can also enforce rules—for example, an enrollment must refer to a student and a course that actually exist.

A database is not just a spreadsheet

A spreadsheet is useful for people to inspect and edit a small set of tabular information. A database system is built to support software access, larger workloads, controlled permissions, concurrent users, and consistent updates. Some databases are relational and use tables; others organize data as documents, key-value pairs, graphs, or other structures.

Queries ask for information

An application sends a query to ask the database for records or to change them. In a relational database, SQL is a widely used language for expressing those queries. The application often communicates with the database through a server or API rather than allowing a user's browser to connect directly to the database.

What to remember