MAC address is a number used by network adapters to uniquely identify themselves. MAC addresses are also known as hardware addresses or physical addresses. A good analogy to this end involves mail delivery: While an IP address can be thought of as your home address something which can most certainly change, and often does- a MAC address is your physical identity- your name, gender, et-cetera. These are features that are unique to you, and just as a MAC address lets a router know what unique system to deliver data to, your name allows a mail carrier to know what unique person to deliver to. Read it more here http://www.pcmech.com/article/in-laymans-terms-2/.