Cloud computing is often a heavy and big term for many. However, cloud computing has been in use for a long time now, without us realising it, or naming it. Cloud computing is when your data is processed in the cloud, instead of computing it locally using your computer hardware. However, to see the final output, a thin client, a computer which has just the sufficient hardware to display the final output, is needed.
SaaS or Software as a Service is probably the best example to demonstrate that the cloud computing was here for more than we realise, although under a thin veil. How long have you been using Gmail? Or Hotmail or Yahoo mail, for that matter. What happens in these email systems? The email is not received locally, they are received on the server of the mail provider. These mail providers then allow you to see the data, in this case, an email, using a local computer.
To add to that, your log in id and password are all stored in the server as well. So, the whole software is in the server, it functions and processes everything in the server but when you want to see the final output, the mail, you can see it using a local PC. That is Software as a Service for you.
Cloud computing is also here, without we realising. Whenever you are using Microsoft Office365, the online version of the popular Office suite, or Google Sheet, which allows you to do data processing on the internet, you are using cloud computing. All these data are stored and processed on the internet and nothing is stored or done locally except for displaying the result.