Adding extra information to a file could be accomplished by adding names of tags(or keywords, labels, subjects, etc.) to the name of the file by hand. By adding information to the name of a file it is perhaps better to find it again. Something else someone could do for better finding it again, is moving the file to another location However, a file can be on one location only. Sometimes even a copy of the file is made in order to find it on several locations. Perhaps it does not matter for you whether the name, the location or the content of a file is modified to add extra information. But perhaps is does.
Tagging for Windows allows you to tag any file or folder without changing the name, location or content of a file or folder. This means you can keep the name and location as you like. It does not seem if the file was modified at some point in time just because of the tagging. If the file is tagged, nothing is changed. This automatically means that if the file is untagged, nothing about being tagged at some point in time can be seen afterwards.
Tags are also the solution for not being able to choose at which location the file should be stored. The tag acts like a virtual folder. If a file has two or more tags, it can be found as part of two or more virtual folders by design. No copies have to be made for finding a document at more locations.