Term: patch

patch is a software update that affects only the component (or potentially that portion of a component) that needs to be updated to resolve an issue.

Rather than updating a complete and potentially very large product for a small number of fixes, patching only updates the components affected, resulting in a much smaller download or installation.

Patching typically happens either of two ways:

  • Only individual files directly affected by the fix are updated. Files not impacted and needing no changes are not re-delivered or reinstalled.
  • Instructions on how to modify the file are downloaded, and the patch process actually modifies the contents of the file to apply the fix. A simple fix might involve instructions that say “change the byte at location 1523 in the file from a 0x74 to 0x75”. This information is often much smaller to transmit and faster to apply than downloading an entire replacement file.

Technically, only the second technique might be called patching, since it’s applying a repair to an existing file without replacing it. The term is, however, typically extended to include patching a product installation by replacing individual files without reinstalling a new version of the application.

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