Android is a flexible operating system, and updates are released for it all the time. Google frequently launches minor tweaks, but more major operation system updates tend to come around once a year, too.
It's important to keep your device as up to date as possible, since bug fixes and security patches are included in the updates.
Depending on what brand of tablet or smartphone you use, you may have to wait to receive the latest updates. For instance, Google makes them available straight away for its own Nexus devices, but Samsung may keep its users waiting a bit longer while it adds on its own, branded, changes to the operating system
Video: How to update your Android tablet
Remember, Android devices come from many different brands, each of which apply their own custom interfaces. In most cases, the directions above should be virtually the same to what you'll find on your own Android tablet or smartphone.