To prove copyright infringement, one must prove ownership of the copyrighted work, that the alleged infringer had access to the work, and that the works are substantially similar, indicating that copying occurred. Access can be proven through direct evidence like acknowledgment, or circumstantial evidence like showing the work was widely available. Copying can also be proven directly or through circumstantial evidence like substantial similarity between the works from the perspective of an ordinary observer. Registration within 5 years of publication establishes a presumption of valid ownership.