Copyrighting an original work is a must to prevent others from capitalizing on your creation and claiming your hard work for their own. Keep in mind that some works can't be protected using this method, as there are very specific rules governing copyright laws. The Balance offers the following information on what can and cannot be copyrighted.
In order for something to copyrighted, it must exist in a tangible form. This includes a wide range of creative works, such as books, sound recordings, articles, lyrics, graphics, pictures, and many others. While these works don't necessarily need to be published, they must be preserved in a physical form and be capable of being reproduced. The definition of what can be copyrighted is actually rather broad and encompasses a number of works not listed here.
Additionally, there are a number of examples of things that cannot be copyrighted. Ideas in their raw form cannot be protected with a copyright. For example, if you give a speech but don't write it down or record it, then it doesn't exist in a tangible form and, as such, cannot be copyrighted. The same can be said of concepts or processes that only exist in a vague form.
Titles and slogans also can't be copyrighted, but they can be protected via trademark.
Lastly, you're also not permitted to copyright something that is considered common property. This includes works that exist in the public domain or those with no actual proof of authorship. When a previous copyright expires, a work is considered to have entered the public domain. This usually involves older works created prior to 1923.