How can variable naming conventions in PHP code impact code readability and maintenance?

Variable naming conventions in PHP code can impact code readability and maintenance by making it easier or harder for developers to understand the purpose of variables. Consistent and descriptive variable names can help other developers (or even yourself in the future) quickly grasp the intention of the code without needing to decipher cryptic names. By following a naming convention, such as using camelCase or snake_case, and choosing meaningful names, you can improve the overall quality and maintainability of your code.

// Bad variable naming convention
$a = 5;
$b = 10;
$result = $a + $b;

// Good variable naming convention
$firstNumber = 5;
$secondNumber = 10;
$sum = $firstNumber + $secondNumber;