Voice search, also called voice-enabled search, allows the user to use a voice command to search the Internet, or a portable device. Currently, voice search is commonly used in (in a narrow sense) "directory assistance", or local search. Examples include Google 411, Tellme directory assistance and Yellowpages.com's 1-800-YellowPages.
In a broader definition, voice search include open-domain keyword query on any information on the Internet, for example in Google Voice Search, Cortana, Siri and Amazon Echo. Given that voice-based systems are interactive, such systems are also called open-domain question answering systems.
Voice search is often interactive, involving several rounds of interaction that allows a system to ask for clarification. Voice search is a type of dialog system.