I came up with an idea but it's similar to another book
Question: I read a book and it gave me a great idea for a book and the book would have some similarities but other than that I think it's completely different and I've seen other things that are sort of similar but they're still there own thing. So do I have a problem?Answer:
Lots of stories are similar to other stories. That's how genres arise. Lots of books are murder mysteries. Lots of books are romances. Lots of books are about zombies. As long as you change enough details of the characters, plot, and setting to make it your own, you should be fine.
Incidentally, regarding "zombies" and other traditional characters: you can use characters and creatures that have been part of human mythology and folklore for centuries. You can also write stories about characters that are now in public domain, such as Robin Hood or Beowulf. You can also write stories about historical figures with certain restrictions (for instance, if their descendents are not still profiting from their image). You may need legal opinion regarding the last one, but certainly a historical figure from 800 years ago would be fair game.
What you cannot ever do is copy the words of another author. The words are copyrighted. You must tell the story in your own words and in your own voice and style.
The general rule is that ideas are not copyrighted, but the expression of those ideas is. So you can use ideas you find in other stories, but the arrangement of those ideas and their expression in prose must be original.