Abstract: A digital personal assistant is described that determines a mental or emotional state of a user based on one or more signals and, based on the determined mental or emotional state, provides the user with feedback concerning an item of content generated thereby or an activity to be conducted thereby. An API is described that can be used by diverse applications and/or services to communicate with the digital personal assistant for the purpose of obtaining information about the current mental or emotional state of the user. Content tagging logic is described that identifies one or more items of content generated or interacted with by the user and stores metadata in association with the identified item(s) of content. The metadata includes information indicative of the current mental or emotional state of the user during the time period when the user generated or interacted with the content.