How can the use of quotation marks affect variable values in PHP?

When using quotation marks in PHP, it is important to note that single quotes and double quotes have different behaviors when it comes to variable interpolation. Single quotes treat variables as literal strings, while double quotes allow for variable interpolation, meaning variables will be replaced with their values. To ensure that variables are properly interpolated, use double quotes when referencing variables within a string.

// Incorrect usage of single quotes
$variable = 'value';
echo 'The variable is $variable'; // Output: The variable is $variable

// Corrected usage with double quotes
$variable = 'value';
echo "The variable is $variable"; // Output: The variable is value