PHP vs HTML, CSS and JavaScript

A website is built from four different tools. Each one has its own job.

An example with all four

Imagine a page that lists blog posts.

• PHP reads the posts from the database and writes the HTML for each one.
• HTML is the result: headings, paragraphs and links.
• CSS styles those headings and paragraphs.
• JavaScript adds a “load more” button that asks the server for the next posts.

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<?php
$posts = ["Learning PHP", "Understanding forms", "Using sessions"];

foreach ($posts as $post) {
    echo "<article><h2>$post</h2></article>\n";
}

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<article><h2>Learning PHP</h2></article>
<article><h2>Understanding forms</h2></article>
<article><h2>Using sessions</h2></article>

The browser gets only this HTML. It does not know that PHP made it.

The simple rule

Ask one question: does this need to happen on the server or in the browser?

• Reading from a database, checking a password or saving a file must happen on the server, so use PHP.
• Opening a menu, validating a field while the user types or animating something must happen in the browser, so use JavaScript and CSS.

Real projects use both. A form can be checked by JavaScript for a fast message and checked again by PHP, because the browser check can always be bypassed. You will see why in PHP Security.

If you are new to the front-end parts, the HTML course, the CSS course and the JavaScript course are on this site.