PHP: “Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” I am running a PHP script, and keep getting errors like:          Notice: Undefined variable: my_variable_name in C:\wamp\www\mypath\index.php on line 10 Notice: Undefined index: my_index C:\wamp\www\mypath\index.php on line 11 Line 10 and 11 looks like this: echo "My variable value is: " . $my_variable_name; echo "My index value is: " . $my_array["my_index"]; What do these errors mean? Why do they appear all of a sudden? I used to use