Only one of the HTML blocks will end up getting sent to the viewer depending on if strstr() returned TRUE or FALSE In other words, if the string MSIE was found or not.
Instead of using a PHP echo statement to output something, we jumped out of PHP mode and just sent straight HTML. The important and powerful point to note here is that the logical flow of the script remains intact. Only one of the HTML blocks will end up getting sent to the viewer depending on if strstr() returned TRUE or FALSE In other words, if the string MSIE was found or not.