Is all matching deterministic, or is there any support for probabilistic matching?

All Profile matching is deterministic and based on first-party data that you've collected.

We do not support probabilistic matching. We’ve found that most marketing automation use cases require 100% confidence that a user is who you think they are (sending an email, delivering a recommendation, etc). We’ve found the best way to support this is through a deterministic identity algorithm.

If you have any questions or see anywhere we can improve our documentation, please let us know or kick off a conversation in the Segment Community!