SEO Course for complete beginner ?

Hello I wan to learn search engine optimization. I am a complete novice. I have read about SEO on various platforms. I want to gain a working knowledge of it.

How did you learn it ? I mostly found some 30 hour courses online.

Are there some complete courses that certify you as an seo ? Most of the courses I found are on udemy coursera and edx, I am not sure about them. Not doubting their credibility, just that they say “specialization “ .

It’s just that most subjects have a university backing like a masters or a diploma or certificate.

And since I am just starting out I want to get my basics right. I am not looking to polish my already existing skills rather looking for a established course which can teach me the basics right.

So if you know a Gold standard course for SEO, please let me know

Thank you !