Cloud computing is where your services ranging from virtual desktop, applications, data is all hosted on servers at a data centre.
You would then be able access these services via an internet connection.
You can access the virtual desktop, applications, data from any machine with an internet connection as everything is hosted on the cloud.
As all the processing is done on the servers in the data center and you also do not need powerful devices in order to use memory intensive applications.
Cloud computing is available on a pay on a cost, per user, per month basis. No large upfront investment on servers is required.