Cloud refers mostly to three things.
- Cloud is often used simply as another word for Internet.
- Cloud storage refers to storing data on a computer somewhere on the Internet not on the computer in your office. People store photos, music and even patient records online.
- Cloud Computing is the sexiest meaning of cloud where the actual computing is done on a computer in the internet not in your office. For example if you ask the computer on your desk to add two plus two the computing is not done in your machine but the numbers are sent to a computer somewhere else, say at MIT in Boston and the numbers are added together there, then the answer is sent back to you at your desk.
This is how cloud base management systems work like Curve and Dentrix Ascend.
(Interestingly the original meaning of cloud computing is none of these now common definitions but actually referred to distributive computing where the power of multiple machines was linked together through the Internet.)