"Siri is a personal assistant application for iOS. The application was first available from the App Store, then came standard on Apple's mobile devices starting with iPhone 4S. Siri uses natural language processing to answer questions and perform actions by delegating requests to an expanding set of web services, including Wolfram|Alpha."
https://www.siriuserguide.com/what-is-wolfram-alpha/ https://www.siriuserguide.com/how-to-use-siri-knowledge/
"Siri Knowledge uses a combination of web searches, inbuilt apps, and Wolfram Alpha to find the answers to a fantastic variety of questions."
If you ask Wolfram Alpha for more information about Siri: https://www.wolframalpha.com/input/?i=Siri
It returns:
"Siri is a personal assistant application for iOS. The application was first available from the App Store, then came standard on Apple's mobile devices starting with iPhone 4S. Siri uses natural language processing to answer questions and perform actions by delegating requests to an expanding set of web services, including Wolfram|Alpha."