A powerful, very versatile yet easy to use tool.
It has many presets for fast settings, can rename using wildcards, regular expressions, translation tools, can number, use tags (ID3, Exif, etc.), can copy, move, link after rename, etc., iterating down in a hierarchy of folders.
Its preview feature avoids bad surprises...
It is old but still valuable.
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Pro Tag management
Can rename using ID3 (music), Exif (photo), IPTC (images), DOC or HTML tags.
Pro Powerful but easy to use
It has many options, including renaming using tags (ID3, Exif...), can number files, use wildcards or regular expressions, walk a hierarchy of folders.
And it has presets for common renaming tasks, like removing parentheses, "Copy (n)" or "Shortcut of", and so on. Its preview feature avoids errors, and warns (a bit late though) of naming conflicts.
Freeware and lightweight (archive is less than 2 MB).
No install, but might need removing options of Explorer integration / scripting if removing.
You can write scripts in VBScript or in JScript (native Windows scripting languages) for complex renaming operations.
Pro Context menu in Explorer
Can add a context menu to Windows Explorer to rename files in a chosen folder.
Pro Has many translations
Available in English, Japanese, French, Spanish and German.
Con Seems to be no longer maintained
Last updated in 2011 (v. 8.4). Yet it works fine in Windows 10 and still does a tremendous job.