What is the purpose of the default created projects in Openstack ?

Hi All, While going through my Openstack setup I got to know that there are 5 projects in the Installation that are visible on the dashboard or from the command line. was wondering that what is the purpose of all these projects that are present here and what would happen if I delete any of those ? can anyone help me with this to get a better understanding of these projects and there purpose? +----------------------------------+--------------------+ | ID | Name | +----------------------------------+--------------------+ | f7ac731cc11f40efbc03a9f9e1d1d21f | admin | | c150ab41f0d9443f8874e32e725a4cc8 | alt_demo | | a9debfe41a6d4d09a677da737b907d5e | demo | | 9208739195a34c628c58c95d157917d7 | invisible_to_admin | | 3943a53dc92a49b2827fae94363851e1 | service | +----------------------------------+--------------------+ Thanks !!