These days there is a real temptation and it’s funny in some strange way to categorize things not only in real life but also in the digital space. To define and categorize music, movies, books, games and another things is catchy. The problem is, that it’s very subjective. For instance, for somebody one book can be "science fiction" but for another "alternate history". It’s based on someone else’s subjectivity.
Tagging and tags is fresh and better alternative of categorizing and grouping things. Tagging allows people to call thing with their own words. They don’t need to conform with keywords or categories in internet created by somebody else. Allow them to describe what they’re seeing in their own words, to imbue the experience with their own meaning. Tagging spares of your time, it creates a variety of tags in different sites and can make the searching for a specific song or a movie or a book or whatever you’re looking for much more easy and faster.
Tags are personal thing. Tagging something is your emotional response and not simply a taxonomic decision. With using tags, people have the control to define things in the web - not only for music, literature, games and movies, but also public websites, data repositories and consultations. Tagging is a new indirect way of control to express your mind and to call things your way - you can call it a "form of freedom of speech" if you want to go that far. Tagging is a power to create your own genres in movies and music for example.
There is also some negative side of tagging and tags - the photos. Not everybody is pleased when is tagged in a photo without his permission- mostly on Facebook. But at the same time tagging is the best way to group and categorize all of your large amount of photos scattered in different folders in the hard drives.