Copyright is more important today than it has ever been before. Technology has come a long way from the past, giving everyone so many resources and different areas to pull research from. There is a downfall though, being that it has become easier to steal people's ideas, images, music, content, etc... Several ways that you can make sure that you cite the work of others ethically is to ask permission from the copyright owner, if granted, acknowledge their work and give thanks, or provide a works cited list.
There are several reasons for why it is important for authors and content creators to protect their intellectual property. One of these reasons are that people can steal your ideas if they aren't copyrighted, and could potentially earn money off of them. If you aren't protected, there is not much that you can do to stop them. There are also people who steal ideas and claim them to be their own. This is not fair to the original content creator, so they should protect their ideas, content, etc... It is also illegal to steal copyrighted material, so if the person is protected, they can do something about it or take legal action against the perpetrator. If you were to ever have any questions about these laws, the United States Copyright Office has a full website dedicated to Copyright, and there is a Copyright Laws section.