Searching in a string

Hello. I have a string, let's say $string and that has several things in it. So, $string=hello,there,world;. I would like to know if I can do a simple if statement to see if world is in $string. world might not always be in $string, so I need to make sure. How can I do this? Thank you in advance. PLEASE EMAIL ME A REPLY. MS Outlook Express will DIE after I visit the php.general news group. It will just freeze. I can look at the posts, but I can't look at anything else without rebooting.