Siri is the voice assistant that comes built in to Apple devices. It can answer questions, translate phrases, set reminders and alarms, find locations, play music, control apps with hands-free "Hey Siri" commands, and more. Apple engineers have even added a few fun Easter eggs to Siri that will return a unique response when you ask it something silly.
With a little practice, you can perform most of your favorite tasks with Siri. It's a great way to quickly send emails and text messages, share photos from the camera roll or the web, set up reminders, play music, and even navigate while driving with Siri on iPhone (iOS 11, 12.0, or later).
In addition to performing basic tasks, Siri can also interact with third-party apps with Siri Shortcuts. These can be anything from a simple phrase like "Order the usual" to a custom action in an app such as Caviar or Waze. Siri will also keep track of how you use your phone and can make suggestions in Messages, Mail, Safari, Apple Music, and more.
If you want to get more out of Siri, it's important to speak clearly and slowly, especially when using hands-free "Hey Siri" commands. It's also worth ensuring your HomeKit scenes and Shortcuts are named properly, that you have a good connection, and that all of your devices have the "Hey Siri" wake word enabled. Lastly, you should always have your device plugged in so it can keep its battery charged and ready to respond to requests.