A sync cable is a cable used to synchronize data contained on two devices. Usually, one of the devices is a laptop or desktop computer and the other is some kind of small mobile device, such as an MP3 player, cell phone, or personal digital assistant (PDA). It is easier to store and organize large amounts of information on a computer than on a small mobile device. As such, it is usually necessary to synchronize the stored and organized information with a cable. Often, that is the only method of information input for portable devices.
Universal serial bus (USB) cables are the most commonly used cables for synchronization. USB ports and cables are used to carry information and energy to and from a great variety of devices; most modern computer peripherals and mobile devices connect to a computer with this type of cable. Because almost all modern computers have USB ports, it is very common for a mobile device to use a USB sync cable. In many cases, the cables used for various devices are actually interchangeable as the same kinds of ports exist both on the device and on the computer.
In most cases, a device's sync cable can also be used to charge the device. Mobile devices tend to be battery powered because it is inconvenient to plug them into an outlet, and it makes them less mobile. It is convenient to charge them while they are synchronizing with the computer, so these cables are designed to accomplish both tasks at the same time. Charging, though, takes significantly longer than synchronizing does, so it is usually necessary to keep the mobile device plugged into the computer for some time after all of the data has been synchronized. Usually, the maker of the mobile device or other third party will produce an attachment for the cable that allows the user to plug it directly into the wall.
This type of cable can come in a variety of different forms. Some are of very high quality and are quite durable, but tend to be relatively expensive, while others are very cheap and thin but often do not last very long. There are cables that are made to be particularly portable, such as the retractable variety, in which the cable is usually stored rolled up but can be unwound and retracted when needed. Some mobile devices now support wireless synchronization, which may eventually replace sync cables.