Copyright law allows you and others to protect certain qualifying works you create. Yet, even if you have a copyright for a particular thing, someone else may still be within their legal rights to make use of it. By the same token, not everything copyrighted by someone else is off limits to you.
Having a clear understanding of the limits of copyrights can avoid you getting into unnecessary legal disputes – either because you feel someone has illegally taken your work. Or they feel you have illicitly used theirs.
The rule of fair use determines when others can use copyrighted work
If you need to assess the situation, here are some thing to consider:
What is the end purpose of the use?
Are you looking to take someone’s work and use it in a voluntary or educational capacity? Or are you looking to take it and exploit it for massive profit?
What quantity of work is used?
The smaller the amount used, the more likely it is to be acceptable to do so.
How original is the work?
Things that anyone could easily produce will probably not get a copyright in the first place. Yet there is still a wide range of original thinking required within work that would qualify.
What financial effect could this have on the owner?
Anything that harms the business interests of another party is more likely to fall fould of fair use doctrine that something that has no foreseeable effect.
If you find yourself in a difficult situation related to copryrighted work seek legal help to understand more about how the law would be applied and your options for resolving things.