Types of USBs and their uses: USB-A A type-A connector is one you've probably used a fair amount. If you've ever purchased these bulk USB cables, they're what you typically plug into a computer USB port when you transfer data, use an external keyboard for typing, or utilize a mouse for a PC. USB-B Type-B connectors are almost square in shape. You've probably seen them when you plug in a printer cable or an external hard drive cable to a computer. But they aren't as common a sight as type-A these days. USB-C One of the newer USB cables on the scene is the type-C. Unlike other connectors, this one is actually reversible, meaning that it can be plugged in upside down if you want. Mini-USB These connectors used to be the standard for mobile devices, cameras, and MP3 players. As their name suggests, they're smaller than a regular USB port. That's why they're often used for smaller devices. Micro-USB The micro allows information to be read without help from a computer, meaning you can connect one device directly to a phone with help from one of these bulk USB cables. USB 3 USB 3 cables are what's known as 'backward compatible,' meaning they actually work with older USB ports and other bulk USB cables. But these cables have different shape pins so they can be used more frequently.