What is an essential characteristic of version control systems?

Version control systems are pivotal in software development as they manage changes to source code over time. An essential characteristic of these systems is their ability to allow users to revert to previous versions of code. This feature is crucial for several reasons: it enables developers to recover from mistakes, test new features without affecting the main codebase, and track the history of changes for accountability and auditing purposes. By maintaining a complete history of modifications, version control systems provide a safety net that allows teams to experiment and innovate while minimizing the risk of introducing errors or losing work.

The other options do not accurately represent the core functions of version control systems. Improving runtime performance typically pertains to optimizations in the code or environment rather than the version control itself. Automatic updates without user input are more commonly associated with deployment tools rather than version control systems. Lastly, compiling code into different languages is the function of compilers and build tools, and not something that version control systems do.