These are the buttons on the page, animations, the locations of the elements, and so on. The frontend is what the user interacts with.
Roughly speaking, this is all that the user does not see on the screen. The backend processes user requests and returns the result. Any website or web application consists of two main parts: backend (server-side) and front end (client-side).
This is how JavaScript was born, becoming one of the most used languages for creating the client-side. In the same year, Brendan Eich was hired by Netscape Communications to expand the programmability of the web. In 1995, one of the most popular browsers was Netscape Navigator.