This column shows the total amount of memory allocated by each process. This is virtual memory and is the sum total of the process's text area (program space), data area, and dynamically allocated area (or "break"). When a process allocates additional memory with the system call "brk", this value will increase. This is done indirectly by the C library function "malloc". The number in this column does not reflect the amount of physical memory currently in use by the process.