Back end web development is where all the behind the scene functionality is added into a static design for example to create a dynamically generated stock list within your website from data stored in a database updated via a seperate admin website used by the site owner usually called a content management system you could also have a search facility where a user enters information about a product or service that you provide and a web page is dynamically generated displaying only the information that the user requires rather than them having to scroll through pages and pages of information to find what they are looking for all of these scenarios require behind the scene programming to enable them to work.
There are many different programming languages and database software available some of most frequently used languages and databses are mentioned below