GitHub Concepts
Internal
Webhooks
A webhook is a mechanism that triggers a HTTP POST invocation into the webhook's external URL, every time a specific event occurs.
A webhook can be installed on an organization or on a specific repository. Once installed, it will be triggered each time one or more subscribed events happen in that organization/repository.
Can be set via UI: Repository -> Settings -> Options: Webhooks.
Webhook Secret
Used by OpenShift for its S2I build strategy.
Pull-Request
Usually, a pull request is initiated from a feature branch and indicates the intent to merge with the develop branch. It is possible to initiate pull requests from a previously cloned repository as well.
The pull requests have to be reviewed, approved and explicitly applied by the owner of the parent repository.
Also see Git cloning.
Required Reviews for Pull Requests
Code Owners
Protected Branch
Security
Personal Access Token
A personal access token is a piece of information that more here... . GitHub grants access to whoever makes a HTTPS invocation and presents this token. A personal access token is similar to a password, in that they should be protected carefully. They are usually though placed in scripts, when building automated CI/CD pipelines. The advantage of using a token instead of a password is that the tokens can be revoked, and then a lot of them can be created.
The list of already generated tokens can be obtained at https://github.com/settings/tokens (account -> Settings -> Developer settings -> Personal access tokens.