This is mostly a legacy page: please see Updates below for current site status.
The domain name learning-python.com hosts two related but distinct websites:
Site History—the books site formerly resided at www.rmi.net/~lutz for some two decades, but was relocated due to quota limits imposed by a former ISP. You can read the story behind its October 2015 relocation at this page.
Browser Portability—these websites have been tested successfully on Chrome, Firefox, Internet Explorer, Opera, and Safari, but Edge is not currently recommended due to its buggy URL popup behavior for lower-left links described on this page.
2017: The former books (a nested books/index.html) and training (the top level's training.html) sites were later merged into learning-python.com—now a single top-level folder which is the union of all other prior parts, also hosts programs and posts, and appeases search engines with HTTP URL redirects via custom Apache .htaccess rewrite rules. Engineers love to change things...
2019: This merged site also eventually became mobile friendly, adopted secure HTTPS, and anonymized IP addresses in analytics data collection for privacy. Its Edge prohibition was also lifted, and its former rmi.net location on EarthLink is scheduled for deletion next year. There's more about all these moves on this page, which is the official replacement for the one you're reading.