Let's expand a couple more spans.
Figure 2.10: Two more spans expanded to show a variety of tags and logs. Each span also contains a section called "Process" that also looks like a collection of tags. The process tags describe the application that was producing the tracing record, rather than an individual span.
In the customer span, we can see a tag http.url that shows that the request at the /customer endpoint had a parameter customer=123, as well as two logs narrating the execution during that span. In the mysql span, we see an sql.query tag showing the exact SQL query that was executed: SELECT * FROM customer WHERE customer_id=123, and a log about acquiring some lock.
What is the difference between a span tag and a span log? They are both annotating the span with some contextual information. Tags typically apply to the whole span, while logs represent some events that happened during the span execution. A log always has a timestamp that falls within the span's start...