As hard drives have become cheaper and bigger , people today find themselves suddenly sitting on a mountain of files which are are organized in a vague or confusing manner. And just when you need that one particular file or document , you just can’t seem to remember its name , So ‘searching’ for becomes useless. One way to prevent such situations from occurring is to use File Tagging .
The traditional way to store files in an orderly fashion would be to adopt Hierarchical folder based on a fixed methodology For example, say you wanted to sort your Movie collection , your folders would look something like this: Movies > (Comedy , Thriller , Action, Drama, etc.)
and inside Action > ( Robots , Racing , Martial arts , etc) Such an organization scheme is very Linear and relies on single organizing method (in this case ‘Movie Genre’). Sure you could go ahead and create sub-folders for other attributes like release year( Eg: Martial arts >(2008 , 2009 ,2010) ) but the main method of organization would still be genre.Also, try to imagine the time and effort that would go into conceptualizing and creating such a system as the number of attributes increased  .
Apart from this , say you wanted to access all movies released in 2008 from your collection , you would have to go through each sub-folder and open the ‘2008’ folder. Looks like my movie collection is deep trouble , here comes file tagging software to the rescue . File – tagging allows you to do the following really useful things:
Assign MULTIPLE tags to a given file
Write small rules/scripts  to AUTOMATICALLY ASSIGN TAGS to certain files Lets go back to the Movie example and see how this makes life easy: Since we’re not using a folder based approach , you could just go ahead and dump all your Movies in one big ‘Movie” folder.
The next step is to tag files according to whichever attributes you feel important
For example, tags for The Karate Kid :(Action, Martial Arts , 2010, Jackie Chan)
Now the next time you want to view Movies from 2010 , just access the tag 2010 , much simpler than before. Here the multiple tags serve as multiple sorting methods for your movie files The next and more awesome step would be to let your files tag themselves. Movie files are commonly named in the following manner TheKarateKid[2010]DVDriP.Xvid-XOR.avi
If your file tagging software could automatically figure out the release year from the file name( with some scripting from you of course!) , it would save you a lot of trouble . Till now i was talking about organizing your Movie folder , well you don’t even need to create a movie folder , just create a huge folder for all your files and tag all your movie files with ‘Movies’ !! Say you’re working on a project with files scattered all across your file-system(across multiple drives or possibly across a network) . You can avoid the need to create something like a Project folder with all your required files copied into it by just tagging  your required files with ‘Project’ . This will save both time and drive space.

There a quite a few file-tagging software’s available , two noteworthy applications are Tabbles and TaggedFrog. Tabbles has demo version allowing you to tag up to 1000 files while TaggedFrog is  free. What i really wonder is why such file-tagging features aren’t available on major operating systems (notable exception is Ubuntu Linux which has some projects which use ExT3 file-systems attributes to create tags.) Further Reading:
[1]Page about Proof  of concept demo of a Tagged File System
[2]Discussion of Tagged File system ideas for Ubuntu (Contains lots of links to other material)