What is the main role of indexes in a database and why are they used?

Indexes in a database serve to speed up search and data retrieval. They work like pointers or tables of contents, allowing quick access to the needed records without scanning all data in the table.

The main roles of indexes:

• Accelerating SELECT operations by quick access to data via a key.
• Improving performance during sorting and joining tables.

However, indexes occupy additional space and slow down insert, update, and delete operations, as the index also needs to be updated.

Example: if you have a users table with an email field, creating an index on email will allow you to quickly find a user by email address without scanning the entire table.