An API (an acronym for 'Application Programming Interface') is a set of rules and specifications that applications can follow to communicate with each other, serving as an interface between different programs like that the user interface facilitates interaction human-software.
Google Search APIs can be used to communicate with the operating system, with databases (DBMS) or with communication protocols (Jabber / XMPP). Multiple social networks have been added (Twitter, Facebook, YouTube, Flickr, LinkedIn, etc.) and other online platforms (Google Maps, WordPress), what has become social media marketing is something else simple, more traceable and therefore more profitable.
Google search result APIs are valuable, first of all, because they allow you to make use of functions already existing in other software (or of the infrastructure already existing in other platforms) so as not to continually reinvent the wheel, thus reusing code that is known to be tested and that works correctly. In the case of proprietary tools (that is, they are not open source), they are a way of letting the programmers of other applications know how to incorporate a specific functionality without having to provide information about how the process is performed internally.
Examples of using web APIs
The developers of any program for Windows that connects to the Internet do not need to include in their code the functions necessary to recognize the network card; for example, a 'call' to the corresponding API of the operating system is enough.
Twitter-related platforms, be they search and filtering mentions like Topsy, or tweet management such as Hootsuite, can make use of the processing capacity of Twitter servers.
The webmasters can include on their websites automatically updated Amazon or eBay products, initiating the process of buying from your website. Or maybe they allow you to identify with Facebook Connect, with the use of Google images API and saving the complex process of user management (and avoiding the Internet user having to register on one more website). Likewise, the "+1" buttons on blogs are called to the Google API.
We can see the use of APIs as a 'subcontracting' of functions. Of course, this outsourcing imposes conditions on the subcontractor: some sites such as Twitter or eBay limit the number of calls that particular software or website can make to its Google Search API in a certain period (per minute, hour, or day) before having to pay a license.
Organizations that identified themselves as more competent in the use of Bing Search APIs had higher incomes and generated more senior levels of customer satisfaction. And practically all executives surveyed (in the field of marketing and ICT) concluded that APIs would have a substantial impact on their businesses in the next 12 months and that it could even increase in the long term. But they also concluded that today, the "API Economy" is fragile: the lack of consistency in API implementations often leads to integration errors after each update ... which can sink from one day to the next. Other than the business of many partners of the providers of those APIs.