Release management is a service management practice inside ITIL 4 that you don't need to know for the ITIL 4 foundation level exam but is going to be covered briefly in this article. The wonderful people over at Dion Training do not just want to leave you just hanging and wondering what this practice is, so they whipped up this discussion.
The purpose of the Release Management practice is to make new and changed services and features available for use. Basically, it's going to provide some set of processes that you're going to have to go through to get the thing from the design all the way out until it's finally live in the environment. Generally, this will involve having a release plan, will have the newer changed infrastructure, newer changed software, and newer changed documentation. Training will also be provided to you and then you'll be able to put it into the deployment and release process. This is where you're going to review it and eventually release it so that it can be deployed into the environment. The whole purpose of release management is that you don't want things to just get put out into the environment without you knowing about it. You want to properly transition them and take them from design, through testing and transition, out and then be released into the operation environment, and make sure that the service desk is ready to support it inside deliver and support.