Siri is a built-in "intelligent assistant" that enables users of Apple products to speak natural language voice commands (e.g. what's the weather like tomorrow) in order to operate a device or its apps. It's context aware, so in the example above it uses your location to identify where you are in order to provide localised weather for you.
Sounds GREAT!, and it kind of is if you can get it to work. Being Scottish means we can't get it to work. No ones developed voice control for the Scottish, frankly, I can understand why - we have about 30 different names for just about everything.
I've chosen to disable Siri on all my devices, and here's why.
So what we're saying is apple needs to know all that to be able to tell me the weather, hmmm, I'm out. I'll give up this convenience in order to keep MY "User Data"