Molly White has a good intro:

Far from being the new hotness attracting glitzy feature stories in tech media or billions in venture funding, RSS has been around for 25 years. [...]

Many, if not most, websites publish an RSS feed. Whereas you can only follow a Twitter user on Twitter or a Substack writer in the Substack app, you can follow any website with an RSS feed in a feed reader. When you open it, all your reading is neatly waiting for you in one place, like a morning newspaper. [...]

I've been heavily using RSS for over a decade, and it's a travesty more people aren't familiar with it. Here's how to join me in the brave new (old) world of RSS:

Previously, previously, previously, previously, previously, previously, previously.