What does this nginx log mean?

Question

Nginx

Hello, tell me what this log means. 188.68.152.239
- - [23/Apr/2015:16:29:01 +0300] "-" 400 0 "-" "-" "-"
looking for a reason. Each visitor has such a log, what is it?

Answer 1

The fact that on 23/Apr/2015:16:29:01 0 bytes were given to the client from the address 188.68.152.239 with a response code of 400, the client data (referrer, agent, etc.) is not defined. See the error log.