Learn the fundamentals of PHP from structural programming to object-oriented techniques.

Web Development with PHP

This highly interactive module introduces us to fundamental programming concepts in PHP—one of the most popular languages in the world. It begins with a simple “Hello, World!” program and proceeds to cover common concepts such as conditional statements, loop statements, and logic in PHP. It then reflects upon the idea of functions and arrays, as well as the power they give to the programmer to write better code.

Finally, it dives deeper into advanced concepts such as classes, inheritance, and exception handling in PHP. By the time we're done, we’ll have a good grip on the basics of PHP and will be ready to study advanced concepts.

Learn PHP from Scratch

# Variables
A variable in any programming language is a named piece of computer memory, containing some information inside. Variables are one of the essential parts of a computer program. You can declare a variable in PHP using a `＄` sign followed by its name,  e.g., `＄myVariable`.

Consider the following PHP code where we store data in two variables and print them.
The `＄str` variable contains a **string**, and the `＄num` variable contains an **integer** data type. We will discuss strings and integers later in the lesson. 

<?php
$str = "I will be back by";
$num = 5;
  
echo $str;
echo " "; // Output: I will be back by
echo $num; // Output: 5
?>

# Data types
Along with the name of variables, their sizes may vary too. In most programming languages (like C++ and Java) you can use different *data types* for your variables. PHP, however, does not have explicit type definitions, but the type of a variable is determined by the type of the value that it is assigned, or by the type that it is [cast](http://php.net/manual/en/language.types.type-juggling.php) to.

There are different data types for different purposes, i.e., **null**, **boolean**, **integer**, **float**, **string**, **object**, **resource**, and an **array**. Here is a brief overview of the types. For a detailed documentation and examples, see the [PHP documentation](http://php.net/manual/en/language.types.php).

## Null
Null can be assigned to any variable. It represents a variable with no value.

This lesson discusses how you can use variables to store data and the various types of these variables, i.e., data types.

Variables and Data Types

Variables