The last thing we will cover in this chapter is the Token API in Drupal 8. We will cover a few theories and, as usual, demonstrate them via examples on our existing "Hello World" module code. We will do this in the context of the mails we are sending out for error logs.
It would be nice if we could include some personalized information in the mail text without having to hardcode it in the module code or configuration. For example, in our case, we might want to include in the email the username of the current user that is triggering the error log that is being emailed.
Let's first understand how the Token API works, before going into our "Hello World" module.