Top command

top - 09:39:16 up 281 days, 13:03,  3 users,  load average: 3.49, 2.81, 2.33
Tasks: 254 total,   2 running, 252 sleeping,   0 stopped,   0 zombie
Cpu(s): 12.3%us,  1.7%sy,  0.0%ni, 71.7%id, 14.3%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:  325058k total, 266795k used,  58263k free,   2517k buffers
Swap:  83858k total,   20589k used,  817999k free, 2390744k cached
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND 6371 Vanita     25   0     46748   6064    2320  R 99.6       0.0           20815:15           scp
23921 oracle    18   0     1.9g      2.7g     2.5g  D  8.3       8.6           0:26.03            oracle
22054 oracle    15   0    1.7g      693m    682m S  1.3      2.2             0:37.01             oracle
 2760 oracle    18   0     1.7g      36m     23m D  1.0        0.1            676:09.89               oracle
 1714 oracle    18   0     627m    159m   35m S  0.3        0.5          2:46.30                 java
24068 oracle    15   0   10992  1168    772 R  0.3           0.0          0:00.55                 top

 “top”, indicates that the system has been up and running for 281  days.
 “Tasks”,  indicates the total number of processes along with a breakdown of running, sleeping, stopped and zombie processes count.
“Cpu(s)”  indicates the current CPU utilization of the system. In this example, CPU is  71.7% idle
 “Mem”  indicates provides the memory information.
"swap" swap memory  information
VIRT stands for the virtual size of a process and it represents how much memory the program is able to access at the present moment
RES stands for the resident size, which is an accurate representation of how much actual physical memory a process is consuming.
SHR indicates how much of the VIRT size is actually sharable .
%CPU CPU % using a process
%MEM  Memory using process
TIME+ elapsed time of process