John Mueller of Google was asked “I’d like to become the greatest SEO ever, what would you advise him to study?” John responded “There are so many interesting facets of what SEOs do, I’d recommend trying out different areas to find one those you’re passionate about.” He then listed off some examples.

He posted these examples on Twitter:

Marketing
Python
Writing
HTML
JavaScript
Usability
Links
Design
User Experience – UXR
… and more.

Here are the set of tweets:

I am a bit surprised he listed links…

Forum discussion at Twitter.