Copyright

The dictionary definition of Copyright is: the exclusive and assignable legal right, given to the originator for a fixed number of years, to print, publish, perform, film, or record literary, artistic, or musical material.[1]
In basic terms If you have created something then you legally own it and no one else can claim that it is thier's. You are also protected if anyone claims that they created something that you did. The only thing with copyright is that there is a lot of loop holes and flaws within it. For instence you cannot copyright protect an idea as an idea is not a physical thing. If you action the idea and create what you were thinking of then that can be copyrighted and protected. Almost anything that has been created can be copyrighted for example a drawing, poem, photograph. The use of the internet has made it more important to copyright your work now because someone could see a piece of your work online and decide to take the image of your work and claim it as thier own. If you have copyrighted it then you own all of the rights to that work.

 There is a few things you can do to protect yourself with copyright for example you could use the copyright symbol with your name next to it on the bottom of your work. You could also post yourself a physical copy of your work within a sealed stamped envelope as this will pass through the mail system and have official date stamps, Although this is not the best way to copyright it still provides a bit of evidence if anything gets took to court. The best way to copyright a piece of work is probably to talk to a copyright lawyer that can help you to choose the best option on how to copyright your work. 
Copyright also does run out after a certain amount of years so its good to renew it after 50 plus years. 

[1] Oxford Dictionary Definition, http://www.oxforddictionaries.com/definition/english/copyright (accessed 16/04/2014)