Unlike (e.g.) the iPhone, Windows 10 phones have a proper file system. OK, so some parts are out of reach on the internal disk, but the rest, plus the whole of a microSD card are open to fiddling. Including geeky file operations like batch renaming. Typically you'd acquire a load of files from another source (e.g. in a ZIP file) and they'd either have weird names or would need extending for clarification. Yes, you could rename them all manually in File Explorer, but you can also batch rename with this UWP utility.

From the Store description:

File Renamer makes it easy to rename large number of files in in a few clicks.

Have a large picture library and wished files were called something more descriptive than DSCsomething.jpg? File Renamer gets the job done without wasting hours.

File Renamer values your privacy and does not send any data on the internet. It is also a native Windows 10 application and takes advantage of all the OS's features on desktop and mobile.

Supported renaming operations

• Changing extension
• Replacing character strings by others
• Inserting a character string
• Moving characters
• Deleting several characters
• Enumeration
• Case conversion (upper, lower, title and sentence case)
• Regular expressions

Operations are not applied immediately: you'll get a preview of any changes before deciding to continue or not. You can chain multiple operations to get virtually unlimited flexibility in how to organize your files.

Some screens of File Renamer UWP in action, here under Windows 10 Mobile, though of course you might have even more use under Windows 10 on the desktop:

Some example screens, showing a file picker (you can also specify folders), the main hamburger function menu, and a detailed control dialog, here for inserting a string of text....

You can grab this free in the Store here.