Methods, systems, and computer readable storage medium related to operating an intelligent digital assistant are disclosed. A plurality of predefined domains each representing a respective area of service offered by an intelligent automated assistant are stored. A text string derived from a user request is obtained, the text string including at least one or more words derived from a speech input received from a user. From the plurality of predefined domains, a relevant domain for the user request is identified based at least on respective degrees of match between the text string derived from the user request and a respective plurality of words associated with each predefined domain. A task is executed in accordance with steps specified in a task flow associated with the relevant domain, and in accordance with one or more task parameters derived from the user request.