Glossary
Real stories from the operations floor, technical deep dives into Sentinel AI, and honest perspectives on where autonomous operations is heading.
- GlossaryWhat Is OpenTelemetry?OpenTelemetry (OTel) is an open-source, vendor-neutral observability framework, a set of APIs, SDKs, a Collector and semantic conventions, for gene...Read the definition →
- GlossaryWhat Is OTLP?OTLP (the OpenTelemetry Protocol) is the standard wire protocol OpenTelemetry uses to transport telemetry, traces, metrics and logs, between SDKs, ...Read the definition →
- GlossaryWhat Is Distributed Tracing?Distributed tracing is a technique that follows a single request as it travels across multiple services, recording each step as a span and linking ...Read the definition →
- GlossaryWhat Is a Span?A span is the basic unit of work in a distributed trace: a single named operation with a start and end time, a set of attributes, a status, and a l...Read the definition →
- GlossaryWhat Is Trace Context Propagation?Trace context propagation is the passing of a request's trace and span identifiers across service boundaries, typically in W3C traceparent headers,...Read the definition →
- GlossaryWhat Are Metrics (Counter, Gauge, Histogram)?Metrics are numeric measurements recorded over time. The three core instrument types are the counter (a cumulative value that only increases), the ...Read the definition →
- GlossaryWhat Are Structured Logs?Structured logs are log records emitted as machine-readable key-value data (often JSON) rather than free-form text, so they can be filtered, aggreg...Read the definition →
- GlossaryWhat Is Telemetry?Telemetry is the data a system emits about its own behaviour, primarily the three signals of traces, metrics and logs (with profiling emerging as a...Read the definition →
- GlossaryWhat Is Observability?Observability is the ability to understand a system's internal state from the telemetry it emits, to the point where you can answer new questions a...Read the definition →
- GlossaryWhat Is the OpenTelemetry Collector?The OpenTelemetry Collector is a vendor-neutral service that receives, processes and exports telemetry through a configurable pipeline of receivers...Read the definition →
- GlossaryWhat Is Auto-Instrumentation?Auto-instrumentation is the automatic capture of telemetry from common libraries and frameworks without writing tracing code, typically through a l...Read the definition →
- GlossaryWhat Is High Cardinality?Cardinality is the number of distinct values a dimension can take. High cardinality means a field with very many unique values, such as user ID or ...Read the definition →
- GlossaryWhat Is PromQL?PromQL is the Prometheus Query Language, used to select and aggregate time-series metrics. It underpins most metric dashboards and alerts and is wi...Read the definition →
- GlossaryWhat Is a Service Map?A service map is an automatically generated topology of your services and how they call each other, derived from distributed traces, showing the de...Read the definition →
- GlossaryWhat Is an SLO?A Service Level Objective (SLO) is a target for a reliability metric over a time window, for example 99.9% of requests succeeding over 30 days. It ...Read the definition →
- GlossaryWhat Is an SLI?A Service Level Indicator (SLI) is the measured quantity that expresses how well a service is performing, such as the proportion of successful requ...Read the definition →
- GlossaryWhat Is an Error Budget?An error budget is the amount of unreliability a service is allowed, calculated as one minus the SLO. If the SLO is 99.9%, the error budget is 0.1%...Read the definition →
- GlossaryWhat Are the Golden Signals?The four golden signals, from Google's SRE practice, are latency, traffic, errors and saturation. Monitoring these four for a user-facing service c...Read the definition →
- GlossaryWhat Is the RED Method?The RED method monitors three request-centric signals for a service: Rate (requests per second), Errors (failed requests), and Duration (latency di...Read the definition →
- GlossaryWhat Is the USE Method?The USE method, from Brendan Gregg, monitors every resource by three signals: Utilization (how busy it is), Saturation (how much work is queued or ...Read the definition →
- GlossaryWhat Is Head vs Tail Sampling?Sampling decides which traces to keep so you do not store all of them. Head sampling decides at the start of a trace (cheap, random, but may drop r...Read the definition →
- GlossaryWhat Are Exemplars?Exemplars are links from an aggregated metric, such as a specific histogram bucket, to an example trace that contributed to it, letting you jump di...Read the definition →
- GlossaryWhat Are Percentiles (p95, p99)?A percentile is the value below which a given share of observations fall. p95 latency is the value 95% of requests are faster than; p99 is the valu...Read the definition →
- GlossaryWhat Are OTel Semantic Conventions?OpenTelemetry semantic conventions are standardised names for attributes and metrics, such as http.request.method or db.system, so that telemetry f...Read the definition →
- GlossaryWhat Are Resource Attributes?Resource attributes are attributes that describe the entity producing telemetry, such as service.name, service.version, host.name or k8s.pod.name, ...Read the definition →
- GlossaryWhat Is Continuous Profiling?Continuous profiling is the ongoing, low-overhead sampling of a running production application to see which functions and lines of code consume CPU...Read the definition →
- GlossaryWhat Is Synthetic Monitoring?Synthetic monitoring proactively tests endpoints and user journeys with scripted probes on a schedule, from outside the system, to detect availabil...Read the definition →
- GlossaryWhat Is Real User Monitoring (RUM)?Real User Monitoring (RUM) captures performance and experience data from actual users' browsers or mobile apps, page load times, web vitals, errors...Read the definition →
- GlossaryWhat Is Agentic AIOps?Agentic AIOps is AIOps in which autonomous AI agents do more than detect and alert: they investigate an incident, decide on a course of action, and...Read the definition →
- GlossaryWhat Is Air-Gapped Observability?Air-gapped observability is running the full observability and AIOps stack inside an isolated network with no internet connectivity, so telemetry c...Read the definition →
- GlossaryWhat Is APM (Application Performance Monitoring)?APM (Application Performance Monitoring) is the practice of measuring the performance and availability of software applications, their latency, thr...Read the definition →
- GlossaryAPM vs Observability: What Is the Difference?APM measures the known performance signals of an application, latency, errors and throughput, with dashboards for expected problems; observability ...Read the definition →
- GlossaryWhat Is Log Aggregation?Log aggregation is the practice of collecting log data from many sources, servers, containers, applications and services, and bringing it into a ce...Read the definition →
- GlossaryWhat Is Log Management?Log management is the end-to-end handling of log data across its lifecycle, collection, aggregation, parsing, storage, retention, search, analysis ...Read the definition →
- GlossaryWhat Is Fluent Bit?Fluent Bit is a lightweight, high-performance open-source (CNCF) log and metrics processor and forwarder. It collects logs from files, containers a...Read the definition →
- GlossaryWhat Is Prometheus?Prometheus is an open-source (CNCF) monitoring system and time-series database that collects metrics by scraping HTTP endpoints on a schedule, stor...Read the definition →
- GlossaryWhat Is a Metrics Dashboard?A metrics dashboard is a visual display of key metrics over time, charts, gauges and tables arranged on one screen, so a team can monitor the healt...Read the definition →
- GlossaryWhat Is Frontend Monitoring?Frontend monitoring is the practice of measuring the performance, availability and errors of the client side of an application, the web page or mob...Read the definition →
- GlossaryWhat Are Core Web Vitals?Core Web Vitals are a set of user-centric performance metrics defined by Google that measure the real-world loading, interactivity and visual stabi...Read the definition →
- GlossaryWhat Is Amazon CloudWatch?Amazon CloudWatch is AWS's native monitoring and observability service. It collects metrics, logs and events from AWS services and your own applica...Read the definition →
- GlossaryWhat Is MCP (Model Context Protocol)?MCP (Model Context Protocol) is an open standard that defines how AI applications and agents connect to external tools, data sources and context. I...Read the definition →
- GlossaryWhat Is RAG (Retrieval-Augmented Generation)?RAG (Retrieval-Augmented Generation) is a technique that improves LLM answers by retrieving relevant information from an external knowledge source ...Read the definition →
- GlossaryWhat Is AI Governance?AI governance is the set of policies, controls and oversight that ensure AI systems are built, deployed and used safely, ethically, transparently a...Read the definition →
- GlossaryWhat Is Microservices Monitoring?Microservices monitoring is the practice of observing the health, performance and interactions of the many small, independent services that make up...Read the definition →
- GlossaryWhat Is Platform Engineering?Platform engineering is the discipline of building and running an internal developer platform, a set of self-service tools, workflows and infrastru...Read the definition →
- GlossaryWhat Is DevOps Observability?DevOps observability is the application of observability within a DevOps practice, instrumenting systems so that development and operations share o...Read the definition →
- GlossaryWhat Is On-Call?On-call is the practice of designating engineers to be available outside normal working hours to respond to production incidents, so that whenever ...Read the definition →
- GlossaryWhat Is an SLA?An SLA (Service Level Agreement) is a formal commitment between a service provider and its customers about the level of service to be delivered, us...Read the definition →
- GlossaryWhat Is Toil in SRE?Toil, in Site Reliability Engineering, is the manual, repetitive, automatable operational work that scales linearly with a service and provides no ...Read the definition →