Syntax Overview of PHP

Syntax Overview of PHP (2025 Edition)

Welcome to phponline.in, your one-stop platform for mastering PHP. This comprehensive, SEO-rich tutorial on Syntax Overview of PHP is designed for complete beginners who want to understand the fundamental structure and rules of PHP programming.

Whether you’re just getting started or brushing up on the basics, this guide will help you build a solid foundation by covering:

• PHP opening and closing tags
• Comments
• Case sensitivity
• Statements and whitespaces
• Variables and data types
• Echo and print statements
• Best coding practices

🔗 Also check: Setting Up PHP Environment to start writing PHP code on your computer.

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What is PHP Syntax?

PHP syntax refers to the set of rules that define how PHP programs are written and interpreted. It defines how PHP code begins, ends, and how various language constructs are used within a PHP script.

Proper syntax ensures that your PHP code is understood correctly by the PHP parser and executes without errors.

PHP Tags

All PHP code must be written inside PHP opening and closing tags. These tags tell the server to interpret the enclosed code as PHP.

<?php
// Your PHP code here
?>

Alternate PHP Tags (Not Recommended)

<?  // Short open tag - not recommended
  echo "Hello, world!";
?>

⚠️ Note: Short open tags ( <? ) are disabled on many servers.

PHP Statements

A statement is a line of code that performs a specific action, and it ends with a semicolon (;).

<?php
echo "Hello, PHP";
?>

Multiple Statements

You can write multiple statements in one PHP block:

<?php
echo "First line";
echo "Second line";
?>

PHP Comments

Comments are ignored by PHP and are used to explain your code.

Single-line Comment:

// This is a single-line comment

Multi-line Comment:

/*
This is a
multi-line comment
*/

PHP Case Sensitivity

In PHP:

• Keywords, functions, and constructs are not case-sensitive.
• Variable names are case-sensitive.

<?php
eCho "This works";
ECHO "This also works";
$Var = "Value";
echo $var; // Error: undefined variable
?>

✅ Tip: Be consistent with casing for readability and maintainability.

PHP Whitespace and Indentation

Whitespace (spaces, tabs, newlines) is mostly ignored in PHP but improves code readability. Indentation helps organize blocks of code.

<?php
if (true) {
    echo "Indented code is easier to read";
}
?>

Echo and Print

Both echo and print are used to output data to the screen.

Echo Example:

<?php
echo "This is PHP";
?>

Print Example:

<?php
print "This is also PHP";
?>

Differences:

• echo can output multiple strings.
• print returns 1 and can be used in expressions.

🔗 Learn more in PHP Output Functions

PHP Variables

Variables in PHP start with the $ symbol.

$greeting = "Hello";
echo $greeting;

Naming Rules:

• Start with $
• Followed by a letter or underscore
• Can contain letters, numbers, underscores
• Cannot contain spaces or special characters

✅ Good Example: $firstName, $user_age ❌ Bad Example: $1user, $user-name

Data Types in PHP

PHP supports several data types:

• String – text
• Integer – whole numbers
• Float (Double) – decimal numbers
• Boolean – true or false
• Array – multiple values
• Object – instances of classes
• NULL – empty variable

Example:

$name = "John"; // string
$age = 30; // integer
$price = 9.99; // float
$isAvailable = true; // boolean

Constants

Constants are defined using define() and do not change.

define("SITE_NAME", "phponline.in");
echo SITE_NAME;

🔗 Read more in PHP Variables and Constants

PHP Blocks and Braces

Blocks of code are wrapped in curly braces {} to define scope.

if ($age > 18) {
  echo "You are an adult.";
} else {
  echo "You are a minor.";
}

Quotation Rules

PHP supports both single and double quotes.

$name = "Alice";
echo "Hello $name"; // Hello Alice
echo 'Hello $name'; // Hello $name

✅ Use double quotes when you want to interpolate variables.

Best Practices for PHP Syntax

• Use meaningful variable names
• Indent nested blocks
• Comment your code
• Follow a consistent naming convention
• Avoid short open tags
• Use strict comparison (===)

 Sample PHP Program

<?php
// This is a sample script
$name = "User";
$greeting = "Welcome to phponline.in!";
echo "Hello, $name! $greeting";
?>

What’s Next?

Now that you understand the basics of PHP syntax, it’s time to move forward.

🔗 Continue to: PHP Variables and Data Types

Frequently Asked Questions (FAQs)

Is PHP case-sensitive?

Variables are case-sensitive, but functions and keywords are not.

What are PHP tags?

PHP tags are used to start and end a PHP script. The standard is <?php ... ?>.

Can I use HTML inside PHP?

Yes. PHP is designed to work with HTML seamlessly.

What’s the difference between echo and print?

Both output data. echo is slightly faster and can take multiple parameters.

What is the best way to write clean PHP code?

Follow proper syntax, use indentation, comments, and meaningful variable names.