USB hubs are a great solution for increasing the number of USB ports on a system without the need for an expansion card.
These hubs come in two formats;
USB Powered - A USB powered hub will be ideal for most application such as using flash drives, connecting a camera to transfer files and so on. Without the need of a mains lead, this is a great portable solution.
Mains Powered - This type of hub has increased power through a mains supply. Powered hubs are great for devices which draw more power such as external hard drives or phone chargers.