Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
Wolfram Alpha is, according to Wikipedia, “an online service that answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer as a search engine might.”
Between Wikipedia and Wolfram Alpha, Apple has done an amazing job in opening up Siri searches to first-class information sources. Unlike Wikipedia queries, which open in the Safari browser, Wolfram Alpha answers are presented directly in the Siri interface. That makes it easy for you to keep going with a conversation, without having to hop into and out of Siri mode on your iPhone (see Figure 2-7).
Figure 2-7. Use Wolfram Alpha queries to check definitions, look up information, calculate, and more.