Hidden updates are updates which are not mentioned in the RuneScape news or the official forums. Jagex used to add many small updates and bug fixes which were too trivial to announce; they now include most of their updates in the Patch Notes sticky of the Recent Updates forum. However, there are still some updates which are not included in the Patch Notes for various reasons. Hidden updates that occur separately from major updates can sometimes also be recognised due to the build changing, which can be found in the Developer's Console.
This page lists hidden updates for 2018.