A CI server is also known as a build server. With teams working on multiple branches, it gets complicated to merge back into the master. CI, in this scenario, plays a key role. CI server hooks provide a way to trigger the build based on the event when code is committed to the repository. Hooks, which are incorporated in almost every version control system, refer to custom scripts that are triggered by specified necessary actions that also occur in a repository. Hooks can run either on the client side or on the server side.
Pull requests are a common way for developers to notify and review each other's work before it is merged into common code branches. A CI server provides a web interface to review changes before adding them to the final project. If there are any problems with the proposed changes, source code can be sent back to the developer to tweak as per the organization's coding requirements.
As shown in the following diagram, server-side hooks in combination...