The response message has the following properties:
## Failure response
If status is fail or warning, an errors element is returned after the status property. The value is a list of errors or warnings encountered. Failure response example.
## Successful response
If the status is not fail, the session element is returned containing the current cuid session and pageTrackingId. These are string values, which contain a mix of alphanumeric and special characters.
Store the cuid in persistent storage and send it to Optimizely in future requests so the same customer can be tracked across multiple sessions (see [Storing customer IDs](🔗)).
The rest of the response includes the appropriate response considering the information of the track and the client tailored customization for the site.