Computer networking is a very precise form of applied science and to understand it completely, you need to study many of its intricacies. One of the things that you need to know while setting up your home's Ethernet or wireless network, is a MAC address. You need these addresses, when setting up a wireless network and configuring your router. One way of securing your wireless network is to use filters based on these addresses, to restrict access. What is a MAC Address? MAC stands for Media Access Control. This address is assigned as a unique identifier to every network adapter, fitted in any device that is connected in an Ethernet or wireless network. Every device connected to the Internet has an inbuilt network interface card that enables its connection to a network. Thus, every device with a network adapter, like your own laptop computer, can be identified by its MAC number. The address, also known as physical or hardware address, is stored in the read only memory of the network interface card. According to the IEEE 802 standard, a convention is set for how these addresses are written. The number is written as a string of six hexadecimal numbers, separated into six groups with two numbers in each. They can be retrieved through the installed operating system on a device. How to Find It? Here are ways in which you can retrieve the address on any operating system. On Windows If you are using a computer operating system of the Windows family (including Windows XP, Windows Vista, and Windows 7), to find the MAC address, you will need to open 'Command Prompt', which can be located in 'Start > Accessories', on Windows Vista and Windows 7 machines. Once you open the command prompt, type in 'cmd'. Then type in 'ipconfig/all'. This will display a list of details, which includes the address. It will be listed as 'Physical Address'. It can be identified as a 12 digit hexadecimal number, separated in groups of two each, with dashes in between. On a Mac To find the address on a Mac OS X Snow Leopard based machine, select 'System Preferences' from the Mac Menu. Among the many icons that you will see in the window that opens next, click on the 'Network' icon. A windows will open with various tabs. To get the address, click on the tab that has 'Ethernet' written on it (if you have an ethernet connection) and it will be displayed as 'Ethernet ID'. To find the wireless network card or airport card address, click on the Airport tab. You will see its address displayed below, as AirPort ID. On Linux On any Linux system, to find the address, you must first be signed in as root. Once you are signed in as the root user, type 'ifconfig -a ' in the command terminal. You will see a lot of information displayed below. The number listed as 'HWaddr' (Hardware Address) is the address of that computer's network adapter. All you have to do is follow the simple instructions explained above and you will be able to retrieve the information you need. Once you find the addresses of the computers that are going to be connected in your home network and add them to the filter list, only they will be granted exclusive access to the network. That way, you can prevent unauthorized access.