Types of Internal table in SAP ABAP

Internal tables can be categoriesed into STANDARD, SORTED and HASHED.

Standard tables have an internal index by default. Records can be accessed by using the index number or with the any key.  The response time always depends on the volume of data in the standard internal table.

Sorted tables also has an internal index but it is pre-sorted by the key. They also have an internal index. Records can be accessed by using the index number or with the any key.  The system uses binary search by default to retrieve the data faster.

Hashed tables have no Internal index and should be accessed by a key which must be specified as unique.  The response time totally depends on the Hash Algorithm.