An external SSD has a fast Solid State Drive. You connect these drives via a Thunderbolt or USB 3.0 port. Thanks to the fast SSD and the connector, it's possible to write and read data much faster (10x) than with a normal external hard drive. For example, an SSD transfers your files 5 to 20 times faster than an HDD, because an SSD contains no moving parts. You can easily connect an external SSD to your computer or laptop with a USB cable.