Why are indexes needed in databases?

Indexes in databases are needed to speed up search and data retrieval. They work like pointers to rows in a table, allowing the DBMS to quickly find the necessary records without scanning the entire table.

For example, if you have a table with millions of records and you often search by the "email" field, creating an index on this field will significantly reduce the execution time of SELECT queries with a condition on email.

However, indexes take up additional space and slow down insert, update, and delete operations, as the index must be maintained in an up-to-date state.