What are the consequences of not defining variables correctly in PHP scripts, as seen in the provided code example?

If variables are not defined correctly in PHP scripts, it can lead to errors such as undefined variable notices or unexpected behavior in the script. To solve this issue, make sure to define variables before using them in the script. This can be done by initializing variables with default values or checking if they are set before using them.

// Incorrect code with undefined variable
echo $name;

// Corrected code with variable defined
$name = "John Doe";
echo $name;