The 'Ok Google' command is an incredible tool, letting you do pretty much everything with your phone without having to lift a finger.
Sure you can just use it for the odd web search but it also lets you set timers and reminders, add calender entries and start up an app. You can make a phone call, get quick wikipedia responses to questions and even ask follow up queries.
It's pretty amazing, but did you know that Google is recording you every time you say those magic words?
By default, the software records what you're saying as a way to help it learn for the future. That means better and faster search results for you and the millions of other people using the service.
You can hear all the things you've tried to say to Google, including the ones it didn't quite manage to catch through this link.
Google Voice & Audio Activity.
It's pretty interesting to see what you've searched for over the years, and also to note the times Google couldn't understand what you said. Of course you can also delete individual searches or everything that has ever been recorded, if you're so inclined.
There doesn't seem to currently be a way to stop Google from recording your words, so bookmark this page if you want to delete things regularly or consider leaving the digital assistant alone if it bothers you.