mac number

[sandbach99]

What is a mac number, where do I find it and what is it for/

[vehelpfulguy]

Do you mean the MAC address of a networking card in a computer ?

http://en.wikipedia.org/wiki/MAC_address

[cyclone]

You have to ask your broadband provider for it so you can change to a new one.

[Ralph]

As vehelpfulguy's link explains, it stands for Media Access Control and is as close as a computer gets to a serial number. It can be changed, so it's not exactly a serial number. Also, if you have multiple network devices on your computer, each will have a MAC address.

To find out what yours is, click Start... Run and in the box that pops up, type cmd and click OK.

An old fashioned DOS window will open up. Type "ipconfig /all" not including the inverted commas. In the stuff that appears, your MAC address will be the Physical Address. If you have multiple networking devices, I think your main MAC address will be the one belonging to the device that you connect to the network (internet) with.

[jenky]

In answer to the second part of your question, one reason to find out your mac address, is when setting up security for a wireless connection.
In the admin area for your wireless router, you can stipulate to allow only certain mac numbers to connect through it, which will prevent anyone else piggybacking on your bandwidth.
(There are obviously other methods of securing wireless networks, but this is pretty simple to set up)