The function is available on Spotlight, the default desktop search tool for OS X and iOS that allows users to search for files on their hard drive and on the Internet. Whenever a user searches for something, Yosemite automatically sends the user's queries and locations to Apple, which then sends the information to Microsoft's Bing to bring users relevant suggestions in the search results. It then displays a pop-up window that says Apple is collecting data to provide searches that are "more relevant to you."
Previously, OS X would notify users when Apple extracts location data by showing a small arrow in the menu bar, but Apple says it has removed the notification as too many of those could "de-sensitize" users.
A report on iOS security also explains in detail what Apple does with the information it collects. The report says Apple gathers five kinds of information from Spotlight: the user's approximate location, the device type, the client app (Spotlight or Safari), the device's language settings and the last three apps used by the user. Furthermore, Apple says data is transmitted over an HTTPS connection and uses a temporary anonymous session ID for a 15-minute period before discarding the ID.
"The anonymous session ID allows Apple to analyze patterns between queries conducted in a 15-minute period," Apple says [pdf]. "For instance, if users frequently search for 'Café phone number' shortly after searching for 'Café,' Apple may learn to make the phone number more available in results."
There are, however, a few concerns. For example, when a journalist searches for a sensitive file stored in his computer, the information is unwittingly sent over to Apple. Although the user and his device will not be linked directly to the query, information about the existing file still gets stored in Apple's servers.
For anyone who could be facing issues like this, Apple says users can always opt out of the service. This is done by going to the OS X's System Preferences, then Spotlight, then Search Results. From there, users can disable "Spotlight Suggestions" and "Bing Web Searches." Safari users also need to disable the service separately by opening Safari and going to Search under Preferences, where they will be able to disable Spotlight Suggestions.
Landon J. Fuller, CEO of software firm Plausible Labs, has also created a simple Python script called Fix-MacOSX, which can be used to disable "the parts of Mac OS X which are invasive to your privacy."
"If we look at Yosemite, we see that Apple collects extremely detailed metrics about their customers' web and Spotlight searches," says Fuller. "They may be using those metrics to explore improvements to their own search technology instead of sell to third-party advertisers, but they're still collecting them."