If you're using a mobile device, there are some situations when it's not convenient to type a search into a search engine. Instead, you can simply talk to your device's intelligent personal assistant. One example is Siri, which comes pre-installed on all new iPhones.
With Siri, you can ask a question like "What's the weather today?" or "Are there any Thai restaurants nearby?" Siri will then try to give you an answer. You can also use Siri to do other things on your device, like setting up reminders. For example, you could say, "Remind me to go to the dentist on Thursday."
For more information, visit Apple's Learn more about Siri page.