--- title: Understanding AppLocker rule collections (Windows 10) description: This topic explains the five different types of AppLocker rules used to enforce AppLocker policies. ms.assetid: 03c05466-4fb3-4880-8d3c-0f6f59fc5579 ms.prod: w10 ms.mktglfcycl: deploy ms.sitesec: library ms.pagetype: security author: brianlic-msft --- # Understanding AppLocker rule collections **Applies to** - Windows 10 This topic explains the five different types of AppLocker rules used to enforce AppLocker policies. An AppLocker rule collection is a set of rules that apply to one of five types: - Executable files: .exe and .com - Windows Installer files: .msi, mst, and .msp - Scripts: .ps1, .bat, .cmd, .vbs, and .js - DLLs: .dll and .ocx - Packaged apps and packaged app installers: .appx If you use DLL rules, a DLL allow rule has to be created for each DLL that is used by all of the allowed apps. >**Important:**  Each app can load several DLLs, and AppLocker must check each DLL before it is allowed to run. Therefore, creating DLL rules might cause performance problems on some computers. Denying some DLLs from running can also create app compatibility problems. As a result, the DLL rule collection is not enabled by default.   For info about how to enable the DLL rule collection, see [Enable the DLL rule collection](enable-the-dll-rule-collection.md). ## Related topics - [How AppLocker works](how-applocker-works-techref.md) - [Understanding AppLocker default rules](understanding-applocker-default-rules.md)