Cross Device Visitor Correlation

1. A method to update applications across multiple computing devices associated with a user, the method comprising: generating application data by an application executing on a computing device; including a visitor identifier in the application data by a data transfer module of the application, the visitor identifier associated with the computing device to uniquely identify a user who uses the computing device and at least one additional computing device and who is not identified at the computing device from a user-provided log-in credential; and communicating the application data with the visitor identifier to a cloud data storage that maintains the application data to update instances of the application on the at least one additional computing device in response to a request from the at least one additional computing device for the application data from the cloud data storage, the update of the instances of the application being effective to update the application data that is configured for display at the at least one additional computing device via a user interface of the application.

2. A method as recited in claim 1 , wherein the at least one additional computing device receives the application data along with the visitor identifier from the cloud data storage to update an instance of the application on the at least one additional computing device, the visitor identifier returned to the cloud data storage with updated application data from the at least one additional computing device.

3. A method as recited in claim 2 , wherein the computing device from which the application data is generated is correlated with the at least one additional computing device that requests the application data based on the visitor identifier.

4. A method as recited in claim 2 , wherein the user of the computing device and the at least one additional computing device is correlated as a same visitor based on the visitor identifier that is included in the application data received from the computing device and included in the updated application data received from the at least one additional computing device.

5. A method as recited in claim 1 , wherein the visitor identifier identifies a unique aspect of the user who is otherwise an unidentified user of the computing device and the at least one additional computing device.

6. A method as recited in claim 1 , wherein the user is correlated with multiple computing devices based on the visitor identifier that is associated with the user who is not identified from the log-in credential or an email address at the multiple computing devices.

7. A method as recited in claim 1 , further comprising receiving a message that is communicated to the computing device for viewing by the user, the message having relevance to the application executing on the computing device; wherein: the visitor identifier is a tracking code received in the message; and the request for the application data from the at least one additional computing device includes the tracking code that is also received in the message at the at least one additional computing device.

8. A method as recited in claim 1 , further comprising receiving a message that is communicated to the computing device; wherein: the visitor identifier is a tracking pixel included in the message; and the request for the application data from the at least one additional computing device includes the tracking pixel that is also included in the message received at the at least one additional computing device.

9. A method to update applications across multiple computing devices associated with a user, the method comprising: receiving application data from a computing device for an application that is executing on the computing device, the application data including a visitor identifier that uniquely identifies a user who uses the computing device and at least an additional computing device and who is not identified at the computing device from a user-provided log-in credential; receiving a request from the additional computing device for the application data to update an instance of the application on the additional computing device; communicating the application data along with the visitor identifier to the additional computing device to update the instance of the application at the additional computing device, the update of the instance of the application effective to update the application data that is configured for display at the additional computing device; receiving updated application data from the additional computing device, the updated application data including the visitor identifier; and correlating the computing device with the additional computing device based on the visitor identifier.

10. A method as recited in claim 9 , further comprising correlating the user of the computing device and the additional computing device as a same visitor based on the visitor identifier that is included in the application data received from the computing device and included in the updated application data received from the additional computing device.

11. A method as recited in claim 9 , wherein the visitor identifier identifies a unique aspect of the user who is otherwise an unidentified user of the computing device and the additional computing device.

12. A method as recited in claim 9 , further comprising correlating the user with multiple computing devices based on the visitor identifier that uniquely identifies the user who is not identified from the log-in credential or an email address at the multiple computing devices.

13. A method as recited in claim 9 , wherein: the visitor identifier is a user identifier that is associated with cloud data storage allocated to the user of the computing devices; and the method further comprises correlating the computing device and the additional computing device with the user based on the user identifier.

14. A method as recited in claim 9 , wherein: the visitor identifier is a tracking code included in a message that is received at the computing device for viewing by the user, the message having relevance to the application executing on the computing device; said receiving the application data that includes the tracking code from the computing device; and said receiving the updated application data from the additional computing device includes the tracking code that is also received in the message at the additional computing device.

15. A method as recited in claim 14 , further comprising: identifying the user based on a message address of the message; and correlating the computing device and the additional computing device with the identified user based on the tracking code.

16. A method as recited in claim 9 , wherein: the visitor identifier is a tracking pixel included in a message that is received at the computing device; said receiving the application data includes the tracking pixel from the computing device; said receiving the updated application data from the additional computing device includes the tracking pixel that is also received in the message at the additional computing device; and the method further comprises correlating the computing device and the additional computing device with the identified user based on the tracking pixel.

17. A method to update applications across multiple computing devices associated with a user, the method comprising: communicating a message for viewing by a user that is associated with at least a computing device and an additional computing device, the message including an incentive related to an application that is executable on the computing device, and the message including a tracking identifier associated with the user; receiving a first visitor identifier from the computing device along with the tracking identifier when the incentive is initiated by the user at the computing device; receiving a second visitor identifier from the additional computing device along with the tracking identifier when the incentive is initiated by the user at the additional computing device; correlating the first visitor identifier and the second visitor identifier to determine a unique identifier of the user based on the tracking identifier received back from the computing device and the additional computing device; and controlling updates to instances of the application on the computing device and the additional computing device according to application data received from the computing device or the additional computing device that is indicative of the unique identifier, the updates effective to update the application data that is configured for display at the computing device or the additional computing device.

18. A method as recited in claim 17 , wherein: the first visitor identifier identifies the computing device; the second visitor identifier identifies the additional computing device; and the method further comprising correlating the user with the computing device and the additional computing device based on the tracking identifier received back from the computing device and the additional computing device.

19. A method as recited in claim 17 , wherein the tracking identifier is one of: a tracking code included in the message; or a tracking pixel included in the message.

20. A method as recited in claim 17 , further comprising: identifying the user based on a message address of the message; and correlating the computing device and the additional computing device with the identified user based on the tracking identifier received back from the computing device and the additional computing device.

21. Computer-readable storage devices comprising one or more applications stored as instructions that are executable and, responsive to execution of the instructions by a computing device, the computing device performs operations for updating applications across multiple computing devices associated with a user, the operations comprising to: receive application data from a computing device for an application that is executing on the computing device, the application data including a visitor identifier that uniquely identifies a user who uses the computing device and at least an additional computing device and who is not identified at the computing device; receive a request from the additional computing device for the application data to update an instance of the application on the additional computing device; communicate the application data along with the visitor identifier to the additional computing device to update the instance of the application at the additional computing device, the update of the instance of the application effective to update the application data that is configured for display at the additional computing device; receive updated application data from the additional computing device, the updated application data including the visitor identifier; and correlate the computing device with the additional computing device based on the visitor identifier.

22. Computer-readable storage devices as recited in claim 21 , wherein the operations further comprise to: correlate the user with multiple computing devices based on the visitor identifier that uniquely identifies the user who is not identified from a log-in credential or an email address at the multiple computing devices.

23. Computer-readable storage devices as recited in claim 21 , wherein: the visitor identifier is a user identifier that is associated with cloud data storage allocated to the user of the computing devices; and the operations further comprise to correlate the computing device and the additional computing device with the user based on the user identifier.

24. Computer-readable storage devices comprising one or more applications stored as instructions that are executable and, responsive to execution of the instructions by a computing device, the computing device performs operations for updating applications across multiple computing devices associated with a user, the operations comprising to: communicate a message for viewing by a user that is associated with at least a computing device and an additional computing device, the message including an incentive related to an application that is executable on the computing device, and the message including a tracking identifier associated with the user; receive a first visitor identifier from the computing device along with the tracking identifier when the incentive is initiated by the user at the computing device; receive a second visitor identifier from the additional computing device along with the tracking identifier when the incentive is initiated by the user at the additional computing device; correlate the first visitor identifier and the second visitor identifier to determine a unique identifier of the user using the tracking identifier received back from the computing device and the additional computing device, the unique identifier determined based on a combination of the computing device and the additional computing device being associated with the user; and control updates to instances of the application on the computing device and the additional computing device according to application data received from the computing device or the additional computing device that is indicative of the unique identifier, the updates effective to update the application data that is configured for display at the computing device or the additional computing device.

25. Computer-readable storage devices as recited in claim 24 , wherein: the first visitor identifier identifies the computing device; the second visitor identifier identifies the additional computing device; and the operations further comprise to correlate the user with the computing device and the additional computing device based on the tracking identifier received back from the computing device and the additional computing device.