Continuous Delivery is automation that deploys your code to a staging or testing environment for end user testing. This allows you to quickly setup your end users to test the functionality and release your changes faster.
In Salesforce terminology, an example of continuous delivery would be creating a package version of your project and installing it in a Partial or Full Copy sandbox.
UPDATE: Salesforce has removed the trailhead module that I originally referenced in this lesson. I've updated the link in the resources section to a public SFDX CI/CD Template on GitLab to use as a reference instead.
Resources:
Salesforce CI/CD GitLab Template - https://gitlab.com/sfdx/sfdx-cic...
