The Platform PM

Glossary and sources

Field Guide

Observability: metrics, logs and traces

10

Glossary and sources

6 min read · Chapter 10 of 10

Words that mean something else here

TermWhat you'd assumeWhat it means here
AgentAn AI agentUsually the collector software on a host; now also an AI agent, often on the same product page
EventSomething that happenedHoneycomb: a wide record (a span is one). Datadog: a log line or a change notification. Security: a SIEM record
CardinalityA row countThe number of unique values of a label, and so the number of metric series
Custom metricA metric you designedAt Datadog, any metric not from one of its integrations, counted per unique name and tag combination
HostA server you ownA billing unit: a VM, a Kubernetes node, or a "host-equivalent" for containers
Ingest vs indexThe same thingIngest is receiving data, priced per GB; indexing makes it searchable for a period, priced per event
SamplingTaking a sample to inspectDropping data on purpose, by a rule
PipelineA CI/CD pipelineA telemetry router that filters, samples and routes
MonitorWatching somethingDatadog's word for an alert rule. In compliance, transaction monitoring (Identity and trust)
SLO, SLA, SLIInterchangeableSLI is the measurement, SLO the internal target, SLA the contract with credits
Error budgetMoneyThe failure you're allowed (1 − the SLO) over a window
Burn rateStartup cash burnHow fast the error budget is being spent; 1x is exactly on budget
IncidentOne thingA reliability incident, a security incident, or an SEC "cybersecurity incident" with a materiality test
AutonomousActs on its ownUsually "investigates without being asked"; few products merge and deploy without a person
CreditA refundAn SLA service credit, or a prepaid unit of AI usage

What surprised me

Placeholders in your voice, drafted from the research and the earlier guides. Rewrite each with your own moment.

"Observability is a tool you buy." Coming from payments, I pictured a product with a price. It turned out to be a set of choices about what to keep, and the same telemetry on the same vendor could cost three times as much depending on how much we indexed.

"Open standards end lock-in." OpenTelemetry made the collection portable. The dashboards, alert rules, query language and two years of history stayed exactly where they were.

"More data, fewer outages." The incidents that hurt were the ones where an alert fired and nobody looked, because it had fired falsely all month.

"Security and observability are merging." The deals say so. The revenue says the security vendors' SIEMs are still several times bigger than the observability vendors' security lines.

"This is a regulated industry like the others." There's no licence and no supervisor. The rules that bit were about what we'd written into the logs.

Sources

Undated entries were read on October 8, 2026; "search result" means seen only as a search snippet or summary. Company figures are self-reported unless they come from a filing or a regulator.

Standards, open source and research

Rules and regulators

Company filings and results

Private companies and deals

Pricing, product and legal pages

Surveys, press and analysis

Field Guides are learning notes, not legal or compliance advice. Rules and fees change; check the cited primary sources before you act on anything here.