When it comes to the application programming interfaces (APIs) and the API economy, the question that gets asked most frequently is "What is an API?" . Thanks to the wider-spread attention that APIs are getting from the mainstream media, "What is an API?" is in fact the million dollar question because for those who understand the potential of APIs, there could be millions of more dollars to be made, or saved.

Answering in a relatively comprehensive but cogent fashion can not only help developers to be more contemplative about fully leveraging the promise of APIs in their wares, it can really jumpstart the conversation that needs to take place between (1) business stakeholders looking for new opportunities and operational efficiencies and (2) the technical staff that's chartered with turning an organization's compute infrastructure into a reflection of the go-forward strategies and objectives. Therefore, establishing a common understanding of what APIs are, how they do what they do, and what some of the most important benefits are is central to moving that conversation forward in a meaningful way.

In creating this seven part series on What are APIs and How Do They Work, ProgrammableWeb editor-in-chief David Berlind turns to some very commonly known real-world metaphors so that readers can more easily understand how APIs fit into our world, what they're used for, and the sorts of opportunities that are unlocked by their underlying architectural principles of standards and abstraction.

In debating what metaphors were applicable, it became clear that none were perfect (somewhat proving the highly unique value proposition of the API). However, some make the power of APIs easier to visualize even if a liberty or two has to be taken in order to bring certain points home. For example, in comparing APIs to electrical wall sockets, the service provider isn't exactly responsible for the last mile of wiring right up to the socket. But, if you'll allow David a few such liberties, his explanation is sure to empower you with a command of the API domain that will be useful in just about any context from consuming developers to API providing organizations.

Finally, this series is one of several that we consider a part of the core curriculum to ProgrammableWeb's API University. As we look to expand this core curriculum (as well as all of the content that API U hopes to offer), it is also our intention to revisit these series and improve both their content and presentation. To that extent, we welcome suggestions and look forward to your feedback in an effort to ensure that ProgrammableWeb is the ultimate destination for maintaining your understanding of the API economy.