Indexing is a data structure technique used to find data more quickly and efficiently in a table. An index is a small table having only two columns. The first column having candidate key of a table and second column contains a set of pointers which is holding the address of the disk block where that particular key value can be found. data is stored like a records.Every record has a key field. Indexing is a data structure technique to efficiently access records from the database files which is work on attributes on the indexing has been done. 

Indexes are of 3 types : 

- Primary indexes  

- Secondary indexes  

- Clustering indexes