Tag System / Mask address

[rodc]

Hi my name is rodc ,
I'm new to the forum and a beginner in php but I know the basics .

I was wondering if anyone would be so kind as to explain to me how to create a tag sytem in php . I'm not exactly interested in the tags as I know that this comes directly from a database connection and what an user enters to describe his/her post .


However and this is the tought question , I was wondering how to make a webpage like:
http://www.delicious.com


I'm trying to create a directory , and for this I need a tag system .
How can I make something like delicous :
if you click on a tag like cellphone
I'm redirected to http://www.delicious.com/popular/cellphone

This is my main question : is delicious creating a new directory for each new tag ???
For instance if I want a tag called home , would delicous create a new directory called home or is this part of an information stored somewhere in a database??

How can they achieve something like this-------->>>> http://www.delicious.com/popular/home

Does this mean that a new directory was created inside /popular named home .... ?

Does every single webpage inside their domain point to new directories (ie. recent , popular , tags ,people ?

Is there a need to create new directories for new entries , tags , etc... Or is this information stored in the database ?

how can they achieve a masking of their address ?
how can they achieve that a webpage like the one listed below would point to the right tag ?




I don't know if I was clear enough but this is something that I'm trying to achieve , so if anybody could help me I would really apreciate it.

Thanks,
rodc

[rodc]

Anyone?? , please I'm desperated to know the solution and how can they have something like this...

Thank you very much,
rodc