I wasn't thinking of the title of the website, or other similar things (like footer copyright, etc)
It's particular phrases and technical terms that get used in multiple places throughout the report - and therefore are used in several of the php files that make up the report.
For example, one section of the report has the heading "INcongruence: How much difference is there between your conscious and unconscious attitudes?"
That one phrase is in four or five different php files (so far), and it occurred to me that I might want to change the wording. There are many more such phrases and terms that similarly are in several php files, and I may decide I'd like to reword some of these - rather than the alternative which is to check every php file to make the changes manually.
So, my thought was that it would be a LOT easier to have such terms and phrases contained in a single language or locale file so that I could change them in a single place and have that automatically change them on the displayed pages every time they're used.
I'm hoping there's an easy way to implement something like this - it's sort of like css for text
I know I could create a database table with all of the terms in it, and then use a database query and echo statements to do what I want - but I thought since I've seen packages like Joomla! and LimeSurvey and the like use language files to achieve this, perhaps there's an easy way to implement it for my needs.