Dark data is the unused, untagged information that piles up inside your storage...

https://lukasnpyy234.cavandoragh.org/gartner-may-2026-agentic-ai-storage-report-what-does-it-mean-for-us

Dark data is the unused, untagged information that piles up inside your storage systems—often making up 55% of all stored data. It raises your risk of ransomware exposure since you may not know what’s vulnerable