Microsoft’s resp. Sysinternals’ Process Explorer for Microsoft Windows

• https://en.wikipedia.org/wiki/Process_Explorer – if you put this article on your watchlist, you will get informed, once somebody updates the latest stable release
• https://blogs.technet.microsoft.com/sysinternals/tag/process-explorer/
• https://docs.microsoft.com/en-gb/sysinternals/
• https://docs.microsoft.com/en-gb/sysinternals/downloads/process-utilities
• https://docs.microsoft.com/en-gb/sysinternals/downloads/process-explorer

N.B.: Running this utility does not require admin privileges.

Allows you to search for files / directories opened by process / applications.

E.g. I had started Excel today, and it “operated” in some directory. I ended Excel, at least I thought so – but it kept running (in “stealth mode”), and it kept “locking” that directory. And when I attempted to remove that directory in Explorer, Explorer wouldn’t let me do so. But of course Explorer did not tell me, who locked that directory. Process Explorer let me search for that directory using a partial name (substring of the full directory name) and identify the process / application in question. That way I got hold of Excel, ended that for real, and eventually I was able to remove that directory. Hurray!