PHP Syntax and Basics: A Comprehensive Guide

By Alessandro D.P. 2 min read February 3, 2026

PHP Syntax Overview

PHP scripts are enclosed within <?php and ?> tags. These tags tell the server to interpret the enclosed code as PHP. While it's common to use <?php for opening tags, some developers may use the short tag <? for brevity, though this is not recommended due to potential compatibility issues.

<?php
echo "Hello, world!";
?>

In the example above, the echo statement outputs the string "Hello, world!" to the browser. This is one of the most common ways to display data in PHP.

Variables and Data Types

In PHP, variables start with a $ symbol followed by the variable name. PHP is a dynamically typed language, which means you don't need to declare the type of a variable explicitly.

<?php
$age = 25;
$name = "Alice";
$isStudent = true;
$gpa = 3.7;
?>

PHP supports several data types:

Type	Description
Integer	Whole numbers (e.g., 42, -7)
Float	Decimal numbers (e.g., 3.14, -0.5)
String	Sequences of characters (e.g., "PHP")
Boolean	True or false values
Array	Collections of values
Object	Instances of classes
Null	Represents no value

Control Structures

Control structures allow you to manage the flow of your program. PHP supports if-else, switch, for, while, and foreach loops.

Conditional Statements

<?php
$score = 85;

if ($score >= 90) {
    echo "A";
} elseif ($score >= 80) {
    echo "B";
} else {
    echo "C";
}
?>

Loops

<?php
// For loop
for ($i = 1; $i <= 5; $i++) {
    echo "Iteration $i<br>";
}

// While loop
$i = 1;
while ($i <= 5) {
    echo "Iteration $i<br>";
    $i++;
}

// Foreach loop
$fruits = ["apple", "banana", "cherry"];
foreach ($fruits as $fruit) {
    echo "$fruit<br>";
}
?>

Functions

Functions in PHP allow you to group code into reusable blocks. You can define your own functions using the function keyword.

<?php
function greet($name) {
    return "Hello, $name!";
}

echo greet("Alice");
?>

PHP also includes a wide range of built-in functions for tasks such as string manipulation, date handling, and file operations.

Arrays

Arrays in PHP can store multiple values in a single variable. They can be indexed or associative.

Indexed Arrays

<?php
$colors = ["red", "green", "blue"];
echo "First color: " . $colors[0];
?>

Associative Arrays

<?php
$student = [
    "name" => "Alice",
    "age" => 22,
    "major" => "Computer Science"
];

echo "Student name: " . $student["name"];
?>