VSS-Virtual Set Size virtual memory consumption (including memory occupied by shared libraries) RSS-Resident Set Size actual physical memory used (including memory occupied by shared libraries) PSS-Proportional Set Size actual physical memory used (proportional allocation Memory occupied by shared libraries) USS-Unique Set Size Physical memory occupied by the process alone (not including the memory occupied by shared libraries) Generally speaking, the memory footprint has the following rules: VSS >= RSS >= PSS >= USS Generally use USS The company uses PSS