---
id: mac-storage-basics.what-is-the-system-photo-library
url: https://storagestudio.us/faq/mac-storage-basics/what-is-the-system-photo-library
category: "Mac storage basics"
subcategory: "Photos, music and video"
question: "What is the System Photo Library in Photos?"
alt_questions:
  - "use as system photo library mac"
  - "change system photo library"
  - "multiple photos libraries mac"
  - "which photos library syncs with icloud"
short_answer: "It's the one Photos library used for iCloud Photos and sharing with other apps. Set it in Photos → Settings → General with Use as System Photo Library."
tags: ["photos", "icloud photos", "library"]
related: ["https://storagestudio.us/faq/mac-storage-basics/where-is-the-photos-library-stored-on-a-mac", "https://storagestudio.us/faq/mac-storage-basics/can-i-have-more-than-one-photos-library"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# What is the System Photo Library in Photos?

The **System Photo Library** is the one library Photos uses for iCloud Photos, Shared Albums and for sharing pictures with other apps. You can have other libraries, but only the system one syncs with iCloud.

To change it, open the library you want in Photos (hold Option at launch to choose), then go to **Photos → Settings → General** and click **Use as System Photo Library**. Switching can trigger a long iCloud sync, so do it deliberately.

For moving the library to an external drive with iCloud in mind, see [iCloud & iCloud Photos](https://storagestudio.us/faq/icloud/).