How can the error "Undefined variable" be resolved in PHP code?

The error "Undefined variable" in PHP occurs when a variable is used without being defined or initialized. To resolve this issue, make sure to define the variable before using it in the code. You can initialize the variable with a default value or assign it a value before using it to avoid the error. Example PHP code snippet:

// Define and initialize the variable to avoid "Undefined variable" error
$variable = "";

// Now you can use the variable without any issues
echo $variable;