Difference between front and back end development?

Answer 1

Front end is a part of web application that works on client side (in browser). So it contains HTML, JavaScript and CSS.
Back end is a part that works on server side (on remote server). It realizes some logic, gives front end content and so on. Platforms vary.

Answer 2

Referring to the other answers; in a nutshell, front-end is the skeleton of your development; the design of your app and how it interacts with the user.

Back-end is the brain of your app and how it functions in the background. Interacting with the database to retrieve data, performing calculations etc.

Answer 3

front end is what you see as a user and back end is the functionality of the website (int the background)