What is CI/CD in software development?

The pipeline is a script that runs on every push: install dependencies, typecheck, run the tests, build, and if all of that passes, deploy. Because it runs on a clean machine rather than yours, it catches the whole category of problems that only exist because of something installed locally, and it makes the deployment identical every time instead of dependent on who ran it.

A pipeline is only worth as much as its checks. Automated deployment with no tests in front of it ships bugs faster and more reliably, which is not the goal. The related failure is a suite people stop trusting: once a test fails intermittently for reasons nobody has fixed, everyone learns to click merge anyway, and the pipeline becomes decoration.