A set of changes done to any program or application with the aim of updating, fixing or improving it is often referred to as what?

A patch is a set of changes made to a program or application, usually to fix bugs or vulnerabilities, update features, or improve performance. It is typically distributed as a small file that contains only the changes necessary to update an existing program, rather than a full installation package. Patches are commonly used to address security vulnerabilities or other issues that can be exploited by attackers. Installing patches is an important part of maintaining the security and reliability of software and systems.