Zapier's Filter tool allows users to set rules for their automated workflows, ensuring that data only passes through if it meets specific conditions. This enables businesses to refine lead qualification, manage projects and calendars, enhance customer engagement, streamline file management, and more, by adding filters at any point after the trigger in a Zap. Filters can be used with various criteria such as text, numbers, dates, and boolean values, and offer features like AND and OR logic, empty field management, and line item management.