Resources
There are a great many Ys and Falcom fan sites out there on the internet, but these are the ones I find the most enjoyable or the most useful.
Official Sites
Lore & General Reference
A highly detailed look at Falcom's main game franchises. Comes packed with references to timelines, characters, music, and more.
Perhaps the premier Ys fan site. Here you'll find dedicated explanations of Ys lore, play order, merchandise, and much, much more.
An archived blog which focused on Falcom games and has some indispensable translation resources. Highly recommended to spend time perusing if you are interested in the history or the people of Falcom.
A wonderful wiki with tons of Ys content. This replaced the old Fandom wikis for a bespoke (and much better) website.
Community Hubs
An incredibly active Discord hub for all Falcom properties and adjacent interests.
Ys's unofficial subreddit.
Gameplay & Mods
A broad (if not fully complete) look at installable mods for many of Falcom's games including the Ys series.
I've created a HowLongToBeat collection of every published Ys game so that you can see how long each game takes to play!
Community member Kaisaan (and friend of the site!) has created an impressive English language patch for the PS2 version of Ys V: Lost Kefin.