A version control system (VCS) is a software tool that helps developers manage changes to source code over time. VCSs allow developers to track changes, collaborate with others, and revert to previous versions of code. Examples of VCSs include Git and Subversion. Join our community Cryptography is the practice of using mathematical algorithms to secure communications and protect information. Cryptography is used in many applications, such as online banking, secure messaging, and digital signatures. Popular cryptographic algorithms include RSA, AES, and SHA.