CI/CD stands for Continuous Integration and Continuous Delivery (or Continuous Deployment). It’s a core practice in modern software development, particularly within a DevOps methodology, that automates the steps required to get new code from a developer’s machine to the end user.

Continuous Integration (CI)

Continuous Integration is the practice of having developers frequently merge their code changes into a central repository, often multiple times a day. The key is that every time a change is merged, an automated system kicks in to build and test the code.

Think of it like a group project where everyone adds their part to a main document. Instead of waiting until the very end to combine everything (and potentially discovering a huge mess of formatting and conflicting ideas), you merge your small updates every day. The CI system is the smart editor that immediately checks if your new additions have broken anything in the main document. If it finds a problem, it alerts the team right away, so you can fix it while the changes are still fresh in your mind. This prevents “integration hell”—the nightmare scenario where you try to merge months of independent work and find it’s full of bugs and conflicts.

Continuous Delivery & Continuous Deployment (CD)

Continuous Delivery and Continuous Deployment are the next steps after Continuous Integration. The “CD” can mean one of two things, and the difference is important:

• Continuous Delivery: This practice ensures that every code change that passes the automated tests is automatically prepared to be released. This means the code is ready to go to a production environment at any time, but it waits for a manual approval from a person (like a product manager or a team lead) before it’s actually deployed to the users. This provides a safety net for teams that want to control when new features go live.
  
• Continuous Deployment: This takes Continuous Delivery a step further. If a code change passes all the automated tests, it is automatically deployed to the live production environment without any human intervention. This is the ultimate goal for many teams as it allows them to ship updates to users incredibly fast and reduces the risk associated with large, infrequent releases. The philosophy is that if you’re making small, frequent changes, the risk of a single change breaking everything is minimal, and any issues that do arise can be quickly fixed in the next small, automated update.

The CI/CD Pipeline

The entire process, from code commit to deployment, is often referred to as the CI/CD pipeline. This is an automated workflow that includes stages like:

1. Build: Compiling the code into a runnable application.
2. Test: Running automated tests (unit tests, integration tests, etc.) to ensure the new code works as expected and hasn’t broken anything.
3. Deliver/Deploy: Packaging the application and making it ready for release.