What are the potential pitfalls of trying to access a variable before it is defined in PHP?

Trying to access a variable before it is defined in PHP can lead to "Undefined variable" notices or errors, which can cause unexpected behavior in your code. To avoid this issue, always make sure to define your variables before trying to access them.

// Define the variable before trying to access it
$variable = "Hello, world!";

// Access the variable after it has been defined
echo $variable;