An iRule is a powerful and flexible feature of BIG-IP devices based on F5's exclusive TMOS architecture. iRules provide you with unprecedented control to directly manipulate and manage any IP application traffic. iRules utilizes an easy to learn scripting syntax and enables you to customize how you intercept, inspect, transform, and direct inbound or outbound application traffic.

iRules is an Event Driven scripting language. This means that you'll be writing code based off of specific Events that occur within the context of the connections being passed through the VIP your iRule is applied to. Here's a list of iRule Events in our Wiki.