An open API (often referred to as a public API) is a publicly available application programming interface that provides developers with programmatic access to a proprietary software application or web service. APIs are sets of requirements that govern how one application can communicate and interact with another. APIs can also allow developers to access certain internal functions of a program, although this is not typically the case for web APIs. In the simplest terms, an API allows one piece of software to interact with another piece of software, whether within a single computer via a mechanism provided by the operating system or over an internal or external TCP/IP-based or non-TCP/IP-based network. Currently, many APIs are provided by organizations for access with HTTP. APIs may be used