IP – Internet Protocol
This is a connectionless protocol, which means that a session is not created before sending data.
IP is responsible for addressing and routing of packets between computers.
It does not guarantee delivery and does not give acknowledgement of packets that are lost or sent out of order as this is the responsibility of higher layer protocols such as TCP.
- ARP – Address Resolution Protocol
Provides IP-address to MAC address resolution for IP packets.
A MAC address is your computer's unique hardware number and appears in the form 00-A0-F1-27-64-E1 (for example).
Each computer stores an ARP cache of other computers ARP-IP combinations.