The front-end of a web application, also known as the client-side, is the portion of the application that users interact with directly. It is responsible for the look and feel of the application, as well as the user interface and user experience. Technologies used in front-end development include HTML, CSS, and JavaScript, along with libraries and frameworks such as React, Angular, and Vue.js.
The back-end of a web application, also known as the server-side, is responsible for the behind-the-scenes functionality of the application. It handles tasks such as storing and retrieving data from a database, processing user input, and handling server-side logic. Back-end developers use server-side languages such as Python, Ruby, Java and PHP, along with frameworks such as Express.js and Ruby on Rails, and databases such as MySQL and MongoDB.
Overall, frontend and backend are two distinct aspects of web development and they interact with each other via APIs.