A technology stack refers to the combination of technologies, programming languages, frameworks, and tools used to develop and run a software application. This includes both the front-end (client side, like HTML and CSS) and back-end (server side, like databases and server configurations) components. A well-defined technology stack enables developers to create applications efficiently while maintaining compatibility and performance. It also helps teams to manage dependencies and integrate different technologies effectively, ultimately leading to faster development cycles and improved application functionality.