CodePipeline

It is a continuous integration and continuous delivery service
It is used for fast and reliable application and infrastructure updates.
It builds, tests, and deploys code every time there is a code change, based on the release process models you define.
It automates the steps required to release software changes continuously.

Example release process using CodePipeline

In this example,

CodePipeline perceives changes in source repository, automatically, after a commit is done
Those changes are built, and if any tests are configured, those tests are run.
Post test completion, built code is deployed to staging servers
CodePipeline runs multiple test like integration/load tests, from staging server
manual approval action is present, after successful completion of CodePipeline tests
approved code is deployed to production instances by CodePipeline