Variables store data. In PHP, they always start with a $ sign.
  
  ## Creating variables
  
  ```php
  <?php
  $name = "John";
  $age = 25;
  $isStudent = true;
  ?>
  ```
  
  ## Common data types
  
  - string: "Hello"
  - integer: 10
  - float: 3.14
  - boolean: true / false
  - array: list of values
  - null: no value
  
  ## Using variables
  
  ```php
  <?php
  echo "My name is $name and I am $age years old.";
  ?>
  ```
  
  PHP replaces variables inside double quotes.
  
  ## Type checking
  
  ```php
  var_dump($age);
  ```
  
  Shows type and value.
  
  > Next: Operators and basic math in PHP.

Understand variables, strings, numbers, booleans, and how PHP handles types.

Variables and Data Types in PHP

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Variables and Data Types in PHP

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