What is an index? Why would you define an index in a table?

What will be an ideal response?

Indexes are created and used to increase performance. For example, if you repeatedly search or sort your data on a specific field, you could create an index to speed up the procedure. An index in Access is similar to an index in a book. It is a lot easier and faster to find a topic in a book's index than having to search through the book page by page to locate what you need. By creating an index for a field or fields in a table, Access can quickly locate all the records that contain specific values for those fields without having to read through each record in the table.