There are two ways of processing large quantities of data in ABAP - either using internal tables or extract datasets.
An internal table is a dynamic sequential dataset in which all records have the same structure and a key. They are part of the ABAP type concept. You can access individual records in an internal table using either the index or the key.
Extracts are dynamic sequential datasets in which different lines can have different structures. Each ABAP program may currently only have a single extract dataset. You cannot access the individual records in an extract using key or index. Instead, you always process them using a loop.
The following section contains examples of how to process large datasets for display in a list: