Why do you learn PHP , html, css and javascript?

Question

Do you know why PHP has been used for webpages like facebook,trivago,etc..?

Answer 1

All of what you mentioned are for Web Development.
php is used for the backend part (connecting to database etc.)

https://www.quora.com/Why-use-PHP

Answer 2

This code may help you ☺
https://code.sololearn.com/Wukw9beaMo55/?ref=app

Answer 3

The languages you mentioned are Web oriented.
So if you don't want to go into web development at all, it will be a waste of time learning them.