Who is connected to my linux system

If you want to see which users are connected to your linux box, the “who” command can let you do the magic. The output will be like below:
[root@localhost ~]# who
root     :0           2007-03-12 04:17
dan     pts/1        2007-03-16 07:07 (
So here two users named root and dan are connected to my linux box.