Please excuse any incorrect term - I'm only partially techy ;-).
I want to be able to create a bulk header and footer that i will reference on hundreds of pages. In other words I want to create a header (i.e. header.php) and footer (i.e. footer.php) pages so I can modify them easily and modifying these 2 pages makes it easy - and then on the hundreds of pages I've referenced these files - those headers and footers automatically change without changing each of those hundreds of files.
Also, do I create these pages outside of WordPress (still on the same server) and just reference the url?
THANKS FOR YOUR HELP!