One of the most important concepts to grasp hold of tightly, when moving from the design of single-user to multi-user FileMaker solutions, is record locking. It's a fairly simple concept to understand. It just prevents two people from editing the same record at the same time. The complex part of record locking is programming your scripts to manage record locking. In this article, I'll start by defining record locking, demonstrate what causes record locking, show you how to test for record locking without hosting your solution and finally how to trap for record locking. I'll also throw in a few examples for good measure so you can measure your newly found skills in the context of a real life scenario.