There are a number of works by that title. To name but two...
The 1977 Billy Joel song is controlled by JoelSongs, and the sound recording is owned by Columbia, which is in turn owned by Sony.
The 2010 Bruno Mars song is controlled by ten different rightsholders but generally administered by Warner, and the sound recording is owned by Elektra, which in turn is also owned by Warner.
You could find your own way and just go with the flow...
Just the one: copyright.
"Copyright obtained" is an unnecessarily wordy way of saying the material is protected by copyright.
no way
"Copyright constraints" is just a way of saying what you want to do is limited by copyright. If you wanted to use a piece of music in a movie, but the fee the rightsholder wanted was beyond your budget, you would say you couldn't use the song due to copyright constraints.
No you cannot "claim" copyright unless you are the original artist/author. Just because you "found" a copy of something does not mean you own the copyright for it. The only way to obtain copyright is to create it yourself, hire someone to create it for you, inherit it, or purchase the rights from the legal owner.
Although it is not required for protection, the copyright symbol is a way to denote the copyright year and rightsholder of a work, such as at the bottom of this page, where it says "Copyright (c) 2011 Answers Corporation."
Materials on the internet are protected by copyright, just as their analog counterparts.
Copyright gives the creator of a work control over its use. A license is a way the copyright owner can allow others to use the work.
Yes, You can CopyRight a domain name for Free.... Just type "CopyRight a Name for Free" at the top of the page.... Choose wisely!
Using protected materials is legal if you have an exemption in the law or permission from the copyright holder.
The only way to register for a copyright in the US is through the Copyright Office within the Library of Congress. See the link below for information and forms.