Before starting a huge PHP related online projects, you should consider using a strategy that will be accesible, readable and maintainable with your other team mates. And one of this strategy is using one php file that contains all of your vital data and information.
This strategy can be compared to a double-edged sword and there is a big chance of being attacked by harmful persons if not used properly. So it's up to the user whether to adopt this kind of strategy or not. Here are the following variables you can fill up, modify and used continously with all your PHP documents. Just don't forget to use the include() function as one of the starting headers for your documents.