Data Structures are a linear collection of ABAP data elements(or raw type), data table types , other data structures or data reference objects. Structures are used as reference types for program data like workareas in programs and as containers for screen elements. Minus(-) symbol is used to reach each component of a data structure. Moreover you can nest a structure into another structure with the keyword .INCLUDE .
Data Structures also provides other facilities like assigning check tables, search helps,currency/quantity fields to components of the structure.
Here i have created a sample structure that contains a component with data element component type, a nested structure, a table type and finally an object reference type.
For .INCLUDE nested structures you can give an aliase for all fields with group option. This helps you move all fields within this group to another structure with ease. For example if you want to reach all fields of nested structure ZYA_STRUCTURE you should just write ZYA_STRUCTURE-ADR.