Duplicate files are exact copies that exist in multiple locations on your computer, taking up unnecessary storage space. Cleanup tools find these duplicates by comparing file names, sizes, creation dates, and crucially, their content (using checksums like MD5 or SHA-256). However, not all duplicates are redundant; some might be intentionally kept in different folders for legitimate reasons, like backups or project versions. Safety depends entirely on verifying why the duplicates exist before deletion.

For example, a photographer might have RAW files and their corresponding edited JPEG copies stored in different folders; deleting the JPEG might not be safe if it's the intended output. A developer might have cloned a Git repository, creating duplicates of source files, where deletion could break the project structure. These tools are commonly found in system utilities like CCleaner, dedicated software like Duplicate Cleaner, and within some OS maintenance features.

Deleting verified true duplicates safely frees up significant storage space and simplifies file management. The primary risk is deleting files needed by applications (e.g., configuration files, document versions) or intentionally saved user files; this can cause program errors or data loss. Always review the duplicates identified by the tool, comparing paths and content previews if possible. Reliable tools offer safe options like moving files to the Recycle Bin first. To ensure safety, never rely solely on the tool's list; critically examine the context and purpose of each duplicate group before confirming deletion.