Can ideas be protected by copyright?

No. Although the work itself may be protected, the idea behind it is not.

For some copyright works people say that it is the expression of an idea that has copyright protection rather then the underlying idea. However, the borderline between expression and idea is very difficult to define - ultimately only the courts can do this.

It is possible that some ideas that are substantially elaborated could attract copyright protection. It is important to remember that if you copy less than the whole of a copyright work thinking that you are only copying the idea behind it, you may actually be copying a substantial part of the copyright work.