Why is it important to know where the variables come from when using $_GET & $_POST in PHP?

It is important to know where the variables come from when using $_GET & $_POST in PHP to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. By validating and sanitizing user input before using it in your code, you can ensure that the data is safe to use. 

// Example of validating and sanitizing user input from $_GET
if(isset($_GET['user_input'])){
    $user_input = filter_var($_GET['user_input'], FILTER_SANITIZE_STRING);
    // Use $user_input safely in your code
}

Keywords

$_GET $_POST variable sourcing security vulnerability data validation

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