What is Cloud computing

This site clear explains what is Cloud Computing.
Reading Wikipedia about clouding computing was nothing but frustration. The only information I found useful from the article was:

Cloud computing derives characteristics from, but should not be confused with:

1. Autonomic computing — "computer systems capable of self-management".[11]
2. Client–server model – Client–server computing refers broadly to any distributed application that distinguishes between service providers (servers) and service requesters (clients).[12]
3. Grid computing — "a form of distributed computing and parallel computing, whereby a 'super and virtual computer' is composed of a cluster of networked, loosely coupled computers acting in concert to perform very large tasks"
4. Mainframe — powerful computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.[13]
5. Utility computing — the "packaging of computing resources, such as computation and storage, as a metered service similar to a traditional public utility, such as electricity";[14]
6. Peer-to-peer – a distributed architecture without the need for central coordination, with participants being at the same time both suppliers and consumers of resources (in contrast to the traditional client–server model).

I just found a very interesting blog post
about History of Programming Languages
I think that post could be a good test to learn how much you know about programming.