What is an API key? Why do I need one?

Application Programming Interface Key (API Key) is a code (alpha-numeric) provided by applications when they are making an API call to identify the calling program. API keys are often referred by many names, such as: app keys, app credentials, or consumer keys. These names are synonymous. API keys help prevent unauthorized access to APIs. The API keys help define access and limits on the use of APIs. When a developer register their application in the developer portal, they are given a consumer key and secret. The consumer key and secret are used to get a token that can be used to perform an API call.