What are indexes used for in database management systems?

Indexes in database management systems are used to speed up the search and retrieval of data. They are created on one or more columns of a table and allow the DBMS to quickly find the needed records without scanning all rows. This is especially important when working with large volumes of data.

Indexes can be:

• Unique — guarantee the uniqueness of values in a column.
• Composite — index multiple columns together.

Example: if you have a users table with an email field, creating an index on this field will allow you to quickly find a user by email.

However, indexes occupy additional space and slow down insert and update operations, so they should be used thoughtfully.