HTML (Hyper Text Markup Language)
HTML is the core elements for designing, implementing and representing documents to be displayed in a web browser.
CSS (Cascading Style Sheets)
CSS represents way of appearance a web page is delivered on web.
JavaScript
JavaScript is an open source & most popular client side scripting language supported by all browsers.
JSON (JavaScript Object Notation)
JSON is open-standard human-readable text file format to transmit data between heterogeneous system.
XML (Extensible Mark-up Language)
XML was the first language to be used as the data transformation between two different systems.