What except front end and what back end?

Answer 1

front end is concerned with the interfaces and design ex. (HTML, CSS, ASP ,,,)
while back end is the core programming or the inner codes, functions, databases etc. ex. (PHP, C#, java ,,,)

Answer 2

Take a random website and look at it.

The front end is what you see, the CSS makes the HTML look appealing to the user (hopefully) however html is supposed to be front end as well however I believe it is only partially.

This is because the back-end is where everything happens. as an example,

you use html and add a form to a website with the general input fields and a submit button. You then have this set to "post" and directed to a php file, in this file are instructions of what to do when the form is submitted. So the HTML form styled with Css is the front end and without the back-end (php) file the form doesn't do anything however arguable the htmls ability to submit makes it partially back end too

To sum it up, front-end displays what the back end tells it to, back-end reads user input and changes its instructions to the front end accordingly.

cheers,
kurios