If you're a gadget-fanatic or just a person who has acquired over time different pieces of equipment from all over the world, then you'll no doubt at some point sit there scratching your head wondering why 'that particular DVD doesn't play in that player' and why 'that game doesn't play on that console'. The reason is of course that different countries around the globe have their own rules and regulations. Here's one example. The USA may decide to release a film for sale to the general public many months before the UK decides it's time. Consequently DVD players here in the UK are fixed so that it is only possible for them to play discs bought over here - unless they are 'chipped'!
Similarly, new phones bought in one country may not necessarily work another. In order to purchase one cheap you will undoubtedly be required to sign a contract for a minimum period of time, which can be up to a year and it will be locked to a network - so you cannot change providers until the contract expires. There are companies out there that can modify your DVD player so that it will play a disc from any country in the world and also your phone so you can decide which network you wish to subscribe to. Be aware though that making unauthorized changes such as these will make the warranty null and void, so in the event of a problem you may have to buy a replacement.