With a data cable, you can transfer data between devices. For example, to make a backup of the photos on your smartphone on your laptop or computer. To connect smartphones to a laptop, you need a cable with USB-A or USB-C at one end, depending on which connector your laptop has. To connect iPhone and most iPad models, you need a Lightning connector on the other end. Most new Android smartphones and tablets have a USB-C connection, which can be recognized by the oval shape. For older and cheaper Android devices, you need an angular micro USB connection. Cables with USB-B can be used to connect printers to your laptop, among other things.