Ranked in these QuestionsQuestion Ranking
Pro Offers instructor-led training
Docker offers in-person training in various places across the world. You can check out the locations and dates here.
You can take an online exam to get a certificate.
Pro Official documentation is beginner-friendly
The official Docker documentation is written in a way that it can act as a tutorial on its own.
Everything is clearly written and directs you to resources if you need further information.