The Web has grown a mindboggling amount in the number of sites, users and implementation capabilities since the first website went live in 1989. Web development is the concept that encompasses all the activities involved with websites and web applications.
Python can be used to build server-side web applications. While a web framework is not required to build web apps, it's rare that developers would not use existing open source libraries to speed up their progress in getting their application working.
If you want to be a web developer it's important to know the foundational tools used to build websites and web applications. It is also important to understand that the core concepts such as HTTP, URLs and HTML were all there at the beginning and then were expanded with new specifications over time. This article on the History of the Web succinctly explains the origins of the web starting from Tim Berners-Lee's origin vision and release at CERN.
The Evolution of the Web visualizes how web browsers and related technologies have changed over time as well as the overall growth of the Internet in the amount of data transferred. Note that the visualization unfortunately stops around the beginning of 2013 but it's a good way to explore what happened in the first 24 years.
The Browser Hacker's Guide to Instantly Loading Everything is a spectacular technical talk given by Addy Osmani at JSConf EU 2017 that has great bits of developer knowledge for both beginner and experienced web developers alike.
Build a web application from scratch and its follow on posts for request handling middleware explores the fundamentals of web development. Learning these foundational concepts is critical for a web developer even though you should still plan to use an established web framework such as Django or Flask to build real-world applications. The open source code for these posts is available on GitHub.
While not Python-specific, Mozilla put together a Learning the Web tutorial for beginners and intermediate web users who want to build websites. It's worth a look for general web development learning.
Web development involves HTTP communication between the server, hosting a website or web application, and the client, a web browser. Knowing how web browsers works is important as a developer, so take a look at this article on what's in a web browser.
Ping at the speed of light dives into the computer networking weeds with how fast packets travel through the internet plumbing. The author created a Python script that scrapes network speeds from disparate locations to see what the network speed is in fiber optic cables as a percentage of the speed of light.
Three takeaways for web developers after two weeks of painfully slow Internet is a must-read for every web developer. Not everyone has fast Internet service, whether because they are in a remote part of the world or they're just in a subway tunnel. Optimizing sites so they work in those situations is important for keeping your users happy.