9. One or more non-transitory computer-readable media as recited in claim 1 , wherein the acts further comprise identifying one or more concepts expressed in the user input; identifying a context associated with the user or associated with a session of the user on a site; and determining an intent of the user input based at least in part on the one or more concepts and the context; and wherein the response is determined based at least in part on the intent and the context.
9. One or more non-transitory computer-readable media as recited in claim 1 , wherein the acts further comprise identifying one or more concepts expressed in the user input; identifying a context associated with the user or associated with a session of the user on a site; and determining an intent of the user input based at least in part on the one or more concepts and the context; and wherein the response is determined based at least in part on the intent and the context. 11. One or more non-transitory computer-readable media as recited in claim 9 , wherein the user input comprises a string of text, and the identifying of the one or more concepts comprises: identifying one or more tokens within the string of text; mapping the one or more tokens to one or more vocab items; and pattern matching the one or more vocab items to the one or more concepts.