How can I create a chat room like http://chat.meta.stackoverflow.com/ in my PHP website? I am looking for a free solution. Please help...
Have you even tried Googling "php chat"? When I do that there are several viable options:
If you mean you want one that works exactly like the Stack Overflow chat... well you're probably out of luck, since that was custom developed for SO. You should be able to modify any of the apps above to look like SO chat.