[mattacular]

Plex is the core component. It allows you to turn a personal collection of digital media into a Netflix-style streaming service available on any of your devices. The UI is very polished and many of the more modern features you'd expect are there as well (such as automatically queueing the next episode of a show). You can also invite friends and family to access your library. Plex provides all of the metadata about the media such as artwork and even subtitles so you don't have to manage that yourself.

The rest of the things mentioned in that post are for discovery/finding and downloading media automatically. Overseerr is for recommendations (? never used it), Radarr and Sonarr automatically get new movies and shows from public trackers and add them to your Plex server.

You can run Plex server on a variety of hardware depending on how many streams you need to support simultaneously.

[Cyph0n]

Just a small note: any media server is the core component. Plex is one popular option, but Emby and Jellyfin (open source) are viable options too.

Overseerr/Jellyseerr is for automatically handling requests. This is only useful if you share access to your server with family or friends.

[xattt]

Subtitles downloaded by Plex are vulnerable to “poisoning”. One set I downloaded was parroting conspiracy theories at the intro and when the credits rolled.

[Cyph0n]

In general, it’s better to run Bazarr for subtitles.

[exe34]

So it's like the FBI warning not to copy DVDs?