It’s how teams keep changes from depending on a person remembering every step. CI means continuous integration (does this change fit with the rest of the code?), and CD means continuous delivery or deployment (once it passes, can it ship?).
Think about an assembly line with inspection stations. A product moves down the line: one station checks parts, one runs a quality test, one packages, one ships. If something fails inspection, the line stops before the bad product reaches the customer. Even a small website can have this: when someone opens a pull request, run the checks; when it merges, build the site; if the build passes, deploy it.
How it shows up
When you work with Claude Code or Codex, the agent may change files and run local tests. CI/CD is that same habit running in the shared system, trusting no one to remember every command. A typical flow: a change lands in git, a pull request opens, the pipeline installs dependencies, runs tests, builds, and reports pass or fail, then can publish to staging or production. It doesn’t make mistakes impossible, though. It only catches what you told it to catch, so an untested bug can still pass, and a bad release may still need a rollback.
Why you care
You don’t need to memorize the acronym, just know where the safety checks happen. If an agent changes code, you want a repeatable inspection line before that code becomes a deployment. The pipeline gives you a calmer question to ask: did the change pass the line? Shipping should be a checked path, not a remembered ritual.