freeCodeCamp/guide/english/php/basic-syntax/index.md

---
title: Basic Syntax
---
# Basic Syntax

A PHP script can be placed anywhere in the document.

A PHP script starts with `<?php` and ends with `?>`

Below, we have an example of a simple PHP file, with a PHP script that uses a built-in PHP function "echo" to output the text "Hello World!" on a web page

```html
<!DOCTYPE html>
<html>
<body>

<h1>My first PHP page</h1>

<?php echo "Hello World!"; ?>

</body>
</html> 
````


The output of that would be :

```` 
My first PHP page

Hello World!
````

#### Note: PHP statements end with a semicolon (;).

# Comments in PHP

PHP supports several ways of commenting:

````
<!DOCTYPE html>
<html>
<body>

<?php
// This is a single-line comment

# This is also a single-line comment

/*
This is a multiple-lines comment block
that spans over multiple
lines
*/

// You can also use comments to leave out parts of a code line
$x = 5 /* + 15 */ + 5;
echo $x;
?>

</body>
</html>
````

# PHP Case Sensitivity

In PHP, all keywords (e.g. if, else, while, echo, etc.), classes, functions, and user-defined functions are NOT case-sensitive.

In the example below, all three echo statements are legal (and equal):

````
<!DOCTYPE html>
<html>
<body>

<?php
ECHO "Hello World!<br>";
echo "Hello World!<br>";
EcHo "Hello World!<br>";
?>

</body>
</html>
````

### However; all variable names are case-sensitive.

In the example below, only the first statement will display the value of the $color variable (this is because $color, $COLOR, and $coLOR are treated as three different variables):

````
<!DOCTYPE html>
<html>
<body>

<?php
$color = "red";
echo "My car is " . $color . "<br>";
echo "My house is " . $COLOR . "<br>";
echo "My boat is " . $coLOR . "<br>";
?>

</body>
</html>
````
fix: change directory structure 2018-10-12 15:37:13 -04:00			`---`
			`title: Basic Syntax`
			`---`
			`# Basic Syntax`

			`A PHP script can be placed anywhere in the document.`

			A PHP script starts with `<?php` and ends with `?>`

			`Below, we have an example of a simple PHP file, with a PHP script that uses a built-in PHP function "echo" to output the text "Hello World!" on a web page`

fix(guide) Replace invalid prism code block names (#35961) * fix: replace sh with shell fix replace terminal with shell fix replace node with js fix replace output with shell fix replace cs with csharp fix replace c++ with cpp fix replace c# with csharp fix replace javasctipt with js fix replace syntax with js fix replace unix with shell fix replace linux with shell fix replace java 8 with java fix replace swift4 with swift fix replace react.js with jsx fix replace javascriot with js fix replace javacsript with js fix replace c++ - with cpp fix: corrected various typos fix: replace Algorithm with nothing fix: replace xaml with xml fix: replace solidity with nothing fix: replace c++ with cpp fix: replace txt with shell fix: replace code with json and css fix: replace console with shell 2019-05-15 10:08:19 -07:00			```html
			`<!DOCTYPE html>`
fix: change directory structure 2018-10-12 15:37:13 -04:00			`<html>`
			`<body>`

			`<h1>My first PHP page</h1>`

			`<?php echo "Hello World!"; ?>`

			`</body>`
			`</html>`
			````


			`The output of that would be :`

			````
			`My first PHP page`

			`Hello World!`
			````

			`#### Note: PHP statements end with a semicolon (;).`

			`# Comments in PHP`

			`PHP supports several ways of commenting:`

			````
			`<!DOCTYPE html>`
			`<html>`
			`<body>`

			`<?php`
			`// This is a single-line comment`

			`# This is also a single-line comment`

			`/*`
			`This is a multiple-lines comment block`
			`that spans over multiple`
			`lines`
			`*/`

			`// You can also use comments to leave out parts of a code line`
			`$x = 5 /* + 15 */ + 5;`
			`echo $x;`
			`?>`

			`</body>`
			`</html>`
			````

			`# PHP Case Sensitivity`

			`In PHP, all keywords (e.g. if, else, while, echo, etc.), classes, functions, and user-defined functions are NOT case-sensitive.`

Removed unnecessary repeated word (#19995) 2018-10-26 18:56:38 +02:00			`In the example below, all three echo statements are legal (and equal):`
fix: change directory structure 2018-10-12 15:37:13 -04:00
			````
			`<!DOCTYPE html>`
			`<html>`
			`<body>`

			`<?php`
			`ECHO "Hello World!<br>";`
			`echo "Hello World!<br>";`
			`EcHo "Hello World!<br>";`
			`?>`

			`</body>`
			`</html>`
			````

			`### However; all variable names are case-sensitive.`

			`In the example below, only the first statement will display the value of the $color variable (this is because $color, $COLOR, and $coLOR are treated as three different variables):`

			````
			`<!DOCTYPE html>`
			`<html>`
			`<body>`

			`<?php`
			`$color = "red";`
			`echo "My car is " . $color . "<br>";`
			`echo "My house is " . $COLOR . "<br>";`
			`echo "My boat is " . $coLOR . "<br>";`
			`?>`

			`</body>`
			`</html>`
			````