Siri analyzes how you use your devices and apps to provide personalized suggestions and better search results using local, on-device processing, and syncs across your devices with end-to-end encryption using iCloud
Siri uses iCloud to sync personalization across your Apple devices using end-to-end encryption.
To make suggestions and search results more relevant, some information is sent to Apple and not associated with you
When you use Siri Suggestions in Search, Look Up, Safari or #images in Messages, any information sent to Apple does not identify you, and is associated with a random, rotating device-generated identifier. Your device may send information such as location, topics of interest (for example, cooking or basketball), your search queries, suggestions you have selected, and related usage data to Apple. This information does not include search results that show files or content on your device. If you subscribe to music or video subscription services, the names of these services and the type of subscription may be sent to Apple. Your account name, number, and password will not be sent to Apple.
This information is used to process your request and provide more relevant suggestions and search results, and is not linked to your Apple ID, email address, or other data Apple may have from your use of other Apple services.
Aggregated information may be used to improve other Apple products and services. Common search queries may be shared with a web search engine to improve search results.
Search Engine Suggestions in Safari
Safari has one field for searches and web addresses so you can browse the web from one convenient place. When Search Engine Suggestions are enabled, Safari will ask your selected search engine for suggestions based on what you’ve typed.
Preload Top Hit in Safari
With Preload Top Hit enabled, as soon as Safari determines a Top Hit based on your bookmarks and browsing history, Safari will begin loading the webpage in the background. If you disable this option, the page will load normally.
You have choice and control
You can control Siri Suggestions in Settings > Siri & Search. If you do not want Siri Suggestions to send your information to Apple, you can turn off Siri Suggestions in Siri & Search. Safari Suggestions can be turned off in Settings > Safari.
You can see and control the full list of features that Siri personalizes and apps that Siri suggests shortcuts for in the Siri & Search section of Settings. To stop apps from contributing information to personalize Siri, go to Siri Settings to disable the Learn from this App toggle in Siri Settings for each app. You can also control here whether Siri can send you suggestions in Search or on the lock screen for each app.
You can turn off Location Services for Siri Suggestions at Settings > Privacy > Location Services > System Services > Location-Based Suggestions. If you turn off Location Services on your device, your precise location will not be sent to Apple. To deliver relevant suggestions, Apple may use the IP address of your Internet connection to approximate your location by matching it to a geographic region.
If you do not want Siri personalization to sync across your devices, you can disable Siri under iCloud settings.