PING sends ICMP ECHO_REQUEST packets to TCP/IP addresses. This program is intended for use in network testing. Basic functionality is identical in all four systems. Advanced functionality does differ some.

ping sends 1 packet each second and returns the status of each - the following is displayed :
PING ( 56 data bytes
64 bytes from icmp_seq=0 H1=128 time=3.2ms
64 bytes from icmp_seq=1 H1=128 time=1.8ms
64 bytes from icmp_seq=2 H1=128 time=1.6ms

Options include
-i n - wait n seconds between pings (the default is 1 second)
ping -i 3 sends pings every 3 seconds

-c n sends only n pings, then stops
ping -c 5 will send 5 pings

-f flood ping. Outputs packets as fast as they come back or one hundred times per second, whichever is more. This can be very hard on a network.
ping -f

-I ifaddr Specify the interface to transmit from on machines with multiple interfaces.
ping -I dc0 will send pings via ethernet card dc0 (or appropriate interface name)

-v verbose. ICMP packets other than ECHO_REPLY that are received are listed
ping -v

see ifconfig to configure a network interface
see netstat to display network connections, etc.