Developers practicing continuous integration merge their changes back to the main branch as often as possible. The developer's changes are validated by creating a build and running automated tests against the build.

• Your team will need to write automated tests for each new feature, improvement or bug fix.
• You need a continuous integration server that can monitor the main repository and run the tests automatically for every new commits pushed.
• Developers need to merge their changes as often as possible, at least once a day.

Continuous delivery is an extension of continuous integration since it automatically deploys all code changes to a testing and/or production environment after the build stage.

This means that on top of automated testing, you have an automated release process and you can deploy your application any time by clicking a button. You can decide to release daily, weekly, fortnightly, or whatever.

• You need a strong foundation in continuous integration and your test suite needs to cover enough of your codebase.
• Deployments need to be automated. The trigger is still manual but once a deployment is started there shouldn't be a need for human intervention.
• Your team will most likely need to embrace feature flags so that incomplete features do not affect customers in production.

Continuous deployment goes one step further than continuous delivery. With this practice, every change that passes all stages of your production pipeline is released to your customers. There's no human intervention, and only a failed test will prevent a new change to be deployed to production.

• Your testing culture needs to be at its best. The quality of your test suite will determine the quality of your releases.
• Your documentation process will need to keep up with the pace of deployments.
• Feature flags become an inherent part of the process of releasing significant changes to make sure you can coordinate with other departments (Support, Marketing, PR...).