Are tags portable, and if so how?
Tags are not 100% portable in that they don't always survive mailing or copying to other computers such as Linux or Windows. On that respect, it's more about those OS supporting the Apple filesystem. I am impressed that even copying tagged files to a SMB formatted USB drive preserves the tag metadata and most copy operations from and to another Mac via an HFS+ hard drive or share does preserve the tags well in practice. (Even copying the file to a 10.8 or older Mac didn't strip tags in my tests).

Apple's article covering tags, http://support.apple.com/kb/HT5839, recommends:


  If you want to include your Tags when sending files through Mail, Messages, or other apps, compress your files and folders before sending them.