The system database contains a large selection of material grades that are supplied with the product and expanded and updated at each release.
A personal database is used to store material grades that you have created yourself. These databases become available the first time you copy materials from the system database, create materials, or import materials.
The database can be stored anywhere, and it can have any name. For example, an appropriate name for a database would be "Plastics Engineer". The materials stored inside a user database are generally stored on single user's machine, and not be accessible to other users.
You can search for material in a personal database.