As a first order of business, I probably should state my limited understanding of how each tool works on the Web. To do so, I whipped up a very high level conceptual model displayed here to give a frame for my questions. One quickly meets the concept front end and back end processes. One does not easily find a definition (that one understands) of what that means in terms of where code executes. My - probably simplistic - understanding is that 'front end' refers to processing that takes place on the client's machine and that 'back end' refers to things that take place (in my model anyway) on a web server running on machines at one's web host. Among other back end processes I envision storing all code that creates webpages that make up a website plus all data that is needed by that code. On the front end, one's browser accepts pages from the backend, displays information on the user interface (mostly commonly a screen, accepts input and requests from keyboard and mouse (and other devices like mics and cameras), and manages communications with the back end and with other Internet resources.
I might be wrong, but I think that HTML, CSS and some javascript actually are executed on the front end but are available to the back end where PHP code is executed and files are accessed and maintained.
I'll stop here and ask those who know more about the process than I do to correct errors of understanding that I've revealed thus far. I have other questions but they hinge on this view of the conceptual model.
Thanks in advance for clarifications and for references that I might study.


