Nowadays, if we are talking about web development, then many web languages are available, but there are two things only: Front-end and back-end.
For front-end, the browser only knows HTML, CSS and javascript. And if we build a website, then we have to know the HTML CSS javascript.
For the back-end, the server sends the response to the browser as per request. One crucial concept comes into the scene, i.e. API, or we can say rest API nowadays.
The server sends the response to the browser in the form of JSON, i.e. javascript object model. And we can show that data over the front-end bg using the library or framework like react, angular, jquery etc.
We will discuss further why we should learn and use react over the angular and jquery in the next lecture.