Identifying a human or machine is disclosed including sending a currently-triggered human or machine identification request to a server, receiving a first operation rendered by the server in response to the human or machine identification request, the first operation being configured to identify a human or machine and expressing an operation track for identifying the human or machine, and sending a second operation that was triggered in response to the first operation to the server to identify the human or machine on a triggering entity for the second operation based on a behavior characteristic model that was set in advance.