Patch
Fix for some flaw or error in software
Patches are created and applied to cover flaws in software applications which may cause errors, crashes, or other unwanted behaviour. Patches for security vulnerabilities are particularly relevant.
Most software includes some flaws, generally minor, due to the complex nature of computer programming. When these flaws are discovered there are two options available to software makers - to replace the flawed software with an entirely new version, or to release a patch, which can be applied to already installed copies of the software, sometimes even while it is still running. Patches may be released on an as-needed basis, responding directly to the discovery of issues, or in some larger companies and applications on a regular cycle, such as Microsoft's monthly Patch Tuesday release.
