A few of these sites offer more extensive paid courses.

Burgundy Wines E-Learning
Vins de Bourgogne, the Burgundy wine trade association, e-Learning site

Comité Champagne Massive Open Online Course
As the name suggests, an online module offered by Comité Champagne, a trade association

Rioja Wine Academy
Free online courses and webinars specific to the Rioja wine region in Spain

School Of Port
If Port is your thing or you want to learn more, you’ll love this site offered by Symington Family Estates, producers of some of the top ports in the world

University of Adelaide Wine Course
Free six-week online course taught by professors from the University of Adelaide covering a diverse range of wine-related topics: descriptive and sensory attributes, grapevine and vineyard development and management, winemaking techniques, and more

Please note that most of these publications have paywalls for a lot of their content.

Decanter
Oldest consumer wine publication in the U.K.

James Suckling
Suckling was one of the first editors for Wine Spectator magazine and started their European Bureau. After 30 years he left the magazine and in 2010 established JamesSuckling.com.

Robert Parker Wine Advocate
Started by one of the OG American wine reviewers.

Vinous
Publication founded by Antonio Galloni, founder of the Piedmont Report, and past critic with Robert Parker’s Wine Advocate.

Wine Enthusiast
Well respected U.S. wine publication

Wine Folly
Overviews and introductory information on a wide variety of wine topics

Wine Spectator
One of the top wine publications for hobbyists and collectors