In SAP, there are many features by default which can be immediately used when you install it. SAP generates the default data for all the masters that can be used immediately. However, your customer may have different requirements from what is available in this standard installation of SAP system. In such cases, you need to customize your installation of SAP system.
SAP system customization is done using SAP Customizing Implementation Guide (IMG) using the command SPRO → IMG.
Any SAP system can be customized in many ways, some of which are as follows: