Web application development is making websites and online programs that people can use from their computers or phones. It's like making an online store or game, but it can also be used to do things like check student grades, pay bills, and even look up recipes. It involves writing software code to make these web applications work and look good. This code is like the instructions a computer needs in order to turn the ideas into a reality. It can be a lot of work, but developers have lots of tools to help them.