If you choose the data class correctly, your table is automatically assigned to the correct area (table space or DB space) of the database when it is created. Each data class corresponds to a physical area in which all the tables assigned to this data class are stored.
There are the following data classes:
Data that is seldom changed. An example of master data is the data contained in an address file, such as the name, address and telephone number.
Data that is frequently changed. An example of transaction data is the goods in a warehouse which change after each purchase order.
Customizing data that is defined when the system is installed and seldom changed. An example is the table with country codes.
Two further data classes, USR and USR1, are provided for the customer. These are for user developments. The tables assigned to these data classes are stored in a table space for user developments. In the following figure you can see tables assigned to different data classes. The figure presents the tables in the ABAP Dictionary and in the database.