Forum Moderators: coopster
Editing template files are the easiest way to make changes in appearances that will appear on all pages using that template (ie. if you want to add an additional logo, or non-forum navigational links).
You will also have to edit many of the .tpl files if you want to add any mods/hacks to your phpbb boards.
Your .php pages on your message boards will use your .tpl files when it generates each page.