What is an API?

• Acronym stands for “Application Programming Interface”

• A contract between two different pieces of software, expressed as a set of function or method calls

• • Another view: a set of questions that can be asked, or requests that can be made

• Example of an individual call in an API: int err = Open(String name, FILE &file) Promise to open the file “name”, place a reference to it in “file”, and return a success/error code