JavaScript is a dynamic, high-level, interpreted programming language that powers the interactive aspects of most websites. jQuery is a fast, small, and feature-rich JavaScript library that simplifies HTML document traversing, event handling, and animation. Coursera's JavaScript and jQuery catalogue teaches you the foundational principles and techniques of these interconnected technologies. You'll grasp the mechanics of JavaScript programming, such as variables, data types, loops, functions, and objects, as well as jQuery methods for manipulating HTML elements, handling events, and creating animations. Moreover, you'll learn to build interactive web applications, debug and optimize code, manage asynchronous operations, and understand the Document Object Model (DOM) manipulation. This comprehensive understanding of JavaScript and jQuery will make you expert in web development and front-end engineering.