You can turn the Today and Notifications views on or off in order to prevent anyone from seeing recent messages that you might have received, and you can turn Siri off here too. The Passbook option can be turned off too, which ensures that no one else can use Passbook to spend your money or use your airline tickets (unless they've got your passcode or one of your fingers.).
Privacy settings in iOS
The next section in iOS Settings is Privacy. This is a key set of features, obviously, but we've actually looked at some of these settings already, as the Privacy panel duplicates several of the settings that can be found in the Restrictions panel within General Settings. We covered the Location Services options when we looked at Restrictions earlier, so we don't need to repeat that information here.
However, your iPhone or iPad apps can share more than just location data. The standard apps that are built into iOS - including the Contacts, Calendar, Photos and Health, can share extensive personal data with other third-party apps that you install on your devices. Any app that wants access to your data - such as Google Maps asking for address info from Contacts - should ask your permission when you first install the app. However, keeping track of all the different apps that you install can get tricky after a while, so the Privacy settings shown here allow you to get a quick overview of all the info that you might be sharing.
Find out what you are sharing, and with whom
The iOS apps that can share your personal info are all listed in Privacy, and if you tap on the name of each app you can see exactly which other third-party apps have asked for permission to share your data.
Some of these might surprise you too - it might make sense for Google Maps to ask for address info from Contacts, but you probably didn't realize that Google Maps has a 'voice search' option that can control your microphone too. That's a legitimate use for the microphone, and of course a wonderful company like Google would never, ever dream of infringing anyone's personal privacy. But in the hands of someone less scrupulous your microphone could potentially be turned into a bugging device that listens to every word you say.
So it's worth checking these Privacy settings every now and then, and turning off any sharing options that don't seem to be absolutely essential.
Let apps share data
It's also worth remembering that the ability to share data between apps is a two-way street. Apple's Health app, for instance, allows third-party health apps to both 'read' and 'write' data. I've got the Nike Running app on my iPhone and this can 'write' my workout and running data to Health, so that Health can compile a better overall picture of my physical condition. However, the Nike app can also 'read' other data, such as my heart rate, from Health and let me know when I'm overdoing things a bit.
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