Learn PHP If you have to learn HTML CSS JS

Learning PHP is not necessary to learn HTML CSS JS
I am learning PHP, but now the book for what is said together, and HTML CSS JS, this looks good dizzy.
Who will explain to me the PHP HTML CSS js do what?
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Yes, we have to learn.
PHP is used to provide dynamic data
HTML for Web page layout
CSS for beautifying pages
JS for manipulating page elements in the browser
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References:

Quote: References:

HTML is the page you see
PHP JS is the processing of data

What's the difference between PHP and JS, and what do you do separately?

PHP is primarily responsible for the background, such as interacting with the database
JS is mainly responsible for the display of the front page, such as you see the picture slide effect, is JS made out.

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