Digital signature is an encrypted communication method that documents and authenticates online transactions around the world and is used to authenticate user identity. The purpose of this paper is to inventory most of the existing techniques that previous researchers have found on the subject of signature verification based on most of the various human biometric features and compare these studies to achieve the best performance and best method of digital signature work in conjunction with biometric features. Through a review of literature and previous research and analysis and comparison, it was concluded that the digital signature based on eye movement tracking is very useful and efficient and fast and serves people with disabilities who cannot interact with the computer naturally and help them to authenticate their identities.