API -Application Programming Interface API stands for Application Programming Interface. An API is a software intermediary that allows two applications to talk to each other. In other words, an API is the messenger that delivers your request to the provider that you're requesting it from and then delivers the response back to you. SOAP - Simple Object Access Protocol – MicroSoft - XMLHttpRequest REST API - Representational State Transfer – Supported by Google XMLHttpRequest + JSON – Look Like a WEB URL OPEN API https://restcountries.eu/rest/v2/all CORS API - Cross Origin Resource Sharing https://api.domainsdb.info/v1/domains/search?domain=facebook&zone=com Will give you Cors Error .To avoid that we need to use proxyserver infront of the url https://cors-anywhere.herokuapp.com/https://api.domainsdb.info/v1/domains/search?domain=facebook&zone=com...