What is the difference between using single quotes and double quotes in PHP when outputting data?

Using single quotes and double quotes in PHP when outputting data can affect how variables and special characters are interpreted. When using double quotes, variables within the string will be evaluated and replaced with their values. However, when using single quotes, variables are treated as literal strings. Additionally, special characters like \n or \t will be interpreted within double quotes but not within single quotes. To ensure that variables are evaluated and special characters are interpreted correctly, use double quotes when outputting data that contains variables or special characters.

$name = "John";
echo "Hello, $name!"; // Output: Hello, John!

// To output the same result using single quotes:
echo 'Hello, $name!'; // Output: Hello, $name!