Can you explain what is meant by an index in a database and what role it performs?

An index in a database is a special data structure that speeds up the search and sorting of records in a table. Essentially, an index is a pointer to the table's rows, sorted by one or more columns.

The role of an index:

• Accelerates SELECT operations, allowing quick retrieval of needed records without scanning the entire table.
• Assists in sorting and joining tables.

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

Example: if there is a users table with an "email" field, creating an index on this field will allow quick searching of users by email.