Cloud computing is simply accessing a computing resource that is based somewhere other than where you are, via the internet.
Most of the world’s most popular websites are a form of cloud computing. Facebook, Gmail and Twitter for example are all effectively applications you are interacting with without ever installing anything.
All the actual ‘work’ or processing, is done at the other end, not on your device (PC, laptop, tablet or even a smartphone). As long as it’s connected to the internet, you can interact with these cloud services with a few clicks.