Modern API development typically conforms to a standard called REST, or Representational State Transfer. A service is RESTful when it conforms to that standard.

REST is most easily identified by its requirements for accessible, easily understood endpoints. For instance, here are three RESTful URLs:

1. http://newco.com/people(GET)
   • View a list of people
2. http://newco.com/people/1(GET)
   • View a person with an ID of 1
3. http://newco.com/people(POST)
   • Create a new person

When a programmer writes code that interacts with those URLs, or loads the URL in their browser, they will be able to see a list of people, view the person with the ID of 1, and create a new person.

Ruby on Rails was one of the early frameworks to truly embrace (and by some accounts force) the usage of REST as a way of transferring data more reliably between multiple endpoints and web services.

There are also many libraries available today that ease iOS and Android development so long as the API conforms to the REST standard. Combining both a modern framework like Ruby on Rails and tools that work easily with REST-based APIs makes for a very powerful, reliable combination to get a lot done more quickly.

Here is another example of a popularAPI provided by Twitter. You can see all the various ways that we can ask the API for information. Now imagine a brand new hire at your company who wants to start developing the next feature againstyourAPI. This is the type of structure they will want to see to begin doing their work quickly within the mobile app. Anything less than such a structured, well-formatted and standardized way of access APIs will very soon be too outdated for modern tools to deal with. So when you are creating your API, be sure to use a framework that can help you support the same standards-based API development methods.