In this first section, we saw how logging works in Drupal 8. Specifically, we covered a bit of theory so that you understand how things play together and you don't just mindlessly use the logger factory without actually having a clue what goes on under the hood.
As examples, we created our own logging channel, which allows us to inject it wherever we need without always having to go through the factory. We will use this channel going forward for the Hello World module. Additionally, we created our own logger implementation. It won't do much at the moment, except getting registered, but we will use it in the next section to send emails when errors get logged to the site.
Finally, we used the logging framework (and our channel) in the salutation configuration form to log a message whenever the form is submitted. In doing so, we also passed the message that was saved so that it also gets included in the log. This should already work with the database log so go ahead and save the configuration form and then check the logging UI for that information message.