Smart collections auto-sort your media by genre, decade, rating, and more. Set them up once and forget about them.
Unlike manual collections where you hand-pick each item, smart collections automatically populate based on rules you define. Add a new sci-fi movie to your library and it automatically appears in your 'Science Fiction' collection — no manual tagging needed.
In your Plex library, click the filter icon. Set your criteria (genre = 'Science Fiction', year > 2020, rating > 7.0 — whatever you want). Once the filter shows the right results, click the '...' menu → 'Create Smart Collection'. Name it and it's live.
Collections appear as posters in your library. You can set the collection mode to 'Hide items in this collection' so individual movies only appear inside the collection poster, not also loose in the library. This dramatically declutters large libraries.
For advanced automation, Kometa (formerly PMM/Plex Meta Manager) creates and maintains collections based on external lists — IMDb Top 250, Trakt trending, TMDb popular, seasonal themes. It runs on a schedule and keeps your collections fresh without any manual work.