Difference Between Webhooks and CI/CDs

Question

I know that Webhooks are used to trigger server-side actions from a hosted git repository, and that CI/CD stands for Continuous Integration & Continuous Deployment/Delivery for a hosted git repository, but what is the key difference, specifically when they are both offered by a single git hosting service provider like GitLab or GitHub? (For GitLab these refer to Webhooks and CI/CD, while for GitHub these refer to Webhooks and GitHub Actions.)

Documentations vaguely details how Webhooks can be and is used to trigger CI/CDs, but meanwhile, vendor-provided CI/CDs can function even when no explicit webhook is added to a git repository. Does this mean that there is a Webhook under the hood for every hosted git repository that uses vendor-provided CI/CD?

My understanding from the above is that explicit Webhooks (contrary to underlying ones) can be used to trigger 3rd party CI/CDs, while git hosting service providers' CI/CDs are hosted and run from the same party. Is this correct?

Thank you very much for whoever posts an answer.

Answer 1

Webhooks and CI/CD are two different technologies that you often find used together.

Webhooks are set up to post data in real time to consuming applications. Webhooks generally post to a URL endpoint that is set up to accept information from it. In the case of CI this could be a webhook that posts information about a commit when it happens. See here for more info - https://codeburst.io/what-are-webhooks-b04ec2bf9ca2

CI/CD exist to automate the deployments and building of software. A common usage for one is to build software for the different environments it may require, e.g. dev, staging, production. A popular CI tool is Team City - https://www.jetbrains.com/teamcity/

To reiterate, webhooks aren't trying to solve the same problem as CI/CD but they do extend the functionality of what it can do.