Copyright protects images and work from being copied and reused by other people. The standard length for copyright is the lifetime of the author/artist and 50 years after they die. Copyright comes into effect immediately; there is no need for registration.
If copyright did not exist, anyone would be able to use and edit any image they found on the web. This would mean that any photo you put on Facebook could be downloaded and edited by anyone who wanted to.
To find an image on Google with no copyright restrictions, you can start a search, and then go to the advanced search. Scroll to the bottom, and then select usage rights. From here you will want to select the parameters that are applicable to your search. Then all you need to do is click search, and your advanced options will be applied.
