Any working website that you see is divided into at least 5 parts. Those parts being:
1. Back-end Programming - Think of this as the brains of the website. The back-end programming is the language that you use to design how the website behaves. Things like what a button does, and what events are triggered after another event happens, etc. are all considered back-end progrmaming.
2. Front-end Design - Think of this as the skin of the website. The front-end has few to none functionalities. Everything you see in the browser is a part of the front-end design.
3. Database - Every long-term data inputted into an application is saved into the database. The database is basically a data-storing table, just like an Excel sheet. The software stores and retrieves information from the database.