A number without a name is noise.
A span without detail is a blank page.
Attributes give telemetry its meaning — the who, what, where, and why.
request_duration: 142ms
A developer sees this metric in a dashboard. They ask: Which endpoint was hit? What HTTP method? Did the request succeed?
The metric alone cannot answer any of these questions.
Choose the attribute that answers each question
"Which endpoint was hit?"
"What HTTP method was used?"
"Did the request succeed?"
metric + attributes
request_duration: 142ms
http.route = "/checkout"
http.request.method = "POST"
http.response.status_code = 200
Attributes work on every signal — not just metrics
span
INSERT orders · 85ms
db.system="postgresql"
db.name="orders"
db.operation="INSERT"
log
ERROR: pool exhausted
pool.name="orders"
pool.max=10
pool.active=10
Attributes are key-value pairs. They turn raw data into answers.