Is torrenting illegal?

[arif12345]

No.  "Torrent" is nothing more than a file transfer protocol.  

What's illegal is pirating software and entertainment media.  When you download a copyrighted film or album or book you are doing the same thing that you'd be doing if you photocopied a book you got at the library.  It's illegal, but who's really going to care if you photocopy a library book or two in your own home?

Where it gets serious is when you are the source, providing free copies of copyrighted material to all comers.  Imagine if you set up a system where anyone, anywhere in the world, could receive a photocopy of any book available at the library just by asking you for it.  Over a period of time, you become world-renowned as a provider of free material to hundreds or thousands (or hundreds of thousands) of people all over the world.  The copyright holders are now losing millions of dollars just because of your activities.  That's when the authorities get interested.

In practice, and with regard to torrents specifically, what this means is that if you download some piece of copyrighted material and fairly quickly shut down your torrent software, you are almost certainly not going to get into any trouble.  There are millions of people all over the world that keep terabytes (or more) of torrents on dedicated servers and keep their software active 24/7.  Those are the people the authorities are interested in, because those are the people taking significant dollars away from the copyright holders.

EDIT: 
Re-reading this today I felt I should correct something.  There are certainly not "millions of people all over the world that keep terabytes (or more) of torrents on dedicated servers".  There are perhaps hundreds of such people, maybe as many as a few thousand at the utmost, but not "millions".