What is the difference between continuous integration (CI) and continuous deployment/delivery (CD)?

Continuous Integration is the practice of frequently merging code changes into a shared branch, with automated builds and tests running on every change to catch integration issues early. Continuous Delivery extends this by ensuring the codebase is always in a deployable state, with releases requiring a manual approval step, while Continuous Deployment goes further still, automatically deploying every change that passes all checks directly to production with no manual gate at all.

# CI: runs on every push/PR
on: [push, pull_request]
jobs:
  build-and-test: { ... }

# CD (Continuous Deployment): auto-deploys after CI passes on main
on:
  push:
    branches: [main]
jobs:
  deploy: { needs: build-and-test, ... }