Summary
JavaScript is a language written for websites to run in the client’s browser.
AJAX is a way for JavaScript to request data from a server without refreshing the page or blocking the application.
jQuery is a JavaScript library built to automate and simplify common web tasks like AJAX or animation.
Angular is a hip JavaScript framework which is made for building large, single-page web applications.
Node.js allows JavaScript to be run without a browser, and is commonly used to run web servers.