Glossary
The OpenTelemetry project uses terminology you may or may not be familiar with. In addition, the project may define the terminology in a different way than others. This page captures terminology used in the project and what it means.
Generic Terminology
Aggregation
The process of combining multiple measurements into exact or estimated
statistics about the measurements that took place during an interval of time,
during program execution. Used by the Metric
Data Source.
API
Application Programming Interface. In the OpenTelemetry project, used to define
how telemetry data is generated per Data Source.
Application
One or more Services designed for end users or other applications.
APM
Application Performance Monitoring is about monitoring software applications, their performance (speed, reliability, availability, etc.) to detect issues, alerting and tooling for finding the root cause.
Attribute
A key-value pair. Used across telemetry signals - e.g. in Traces to
attach data to a Span, or in Metrics. See attribute
spec.
Automatic Instrumentation
Refers to telemetry collection methods that do not require the end-user to modify application’s source code. Methods vary by programming language, and examples include bytecode injection or monkey patching.
Baggage
A mechanism for propagating name/value pairs to help establish a causal relationship between events and services. See baggage spec.
Client Library
See Instrumented Library.
Client-side App
A component of an Application that is not running inside a
private infrastructure and is typically used directly by end-users. Examples of
client-side apps are browser apps, mobile apps, and apps running on IoT devices.
Collector
A vendor-agnostic implementation on how to receive, process, and export telemetry data. A single binary that can be deployed as an agent or gateway.
Also known as the OpenTelemetry Collector. More on the Collector here.
Contrib
Several Instrumentation Libraries and the
Collector offer a set of core capabilities as well as a
dedicated contrib repository for non-core capabilities including vendor
Exporters.
Context Propagation
Allows all Data Sources to share an underlying context
mechanism for storing state and accessing data across the lifespan of a
Transaction. See context propagation
spec.
DAG
Data Source
See Signal
Dimension
See Label.
Distributed Tracing
Tracks the progression of a single Request, called a
Trace, as it is handled by Services that make up an
Application. A Distributed Trace
transverses process, network and security boundaries.
More on Distributed Tracing here.
Event
Something that happened where representation depends on the
Data Source. For example, Spans.
Exporter
Provides functionality to emit telemetry to consumers. Used by
Instrumentation Libraries and the
Collector. Exporters can be push- or
pull-based.
Field
Name/value pairs added to Log Records (similar to
Attributes for Spans and Labels for
Metrics). See field spec.
gRPC
A high-performance, open source universal RPC framework. More on gRPC
here.
HTTP
Short for Hypertext Transfer Protocol.
Instrumented Library
Denotes the Library for which the telemetry signals
(Traces, Metrics, Logs) are gathered. See
more.
Instrumentation Library
Denotes the Library that provides the instrumentation for a given
Instrumented Library.
Instrumented Library and
Instrumentation Library may be the same
Library if it has built-in OpenTelemetry instrumentation. See
more.
JSON
Short for JavaScript Object Notation.
Label
See Attribute.
Language
Programming Language.
Library
A language-specific collection of behavior invoked by an interface.
Log
Sometimes used to refer to a collection of Log Records. May be
ambiguous, since people also sometimes use Log to refer to a single
Log Record, thus this term should be used carefully and in the
context where ambiguity is possible additional qualifiers should be used (e.g.
Log Record). See more.
Log Record
A recording of an Event. Typically the record includes a timestamp
indicating when the Event happened as well as other data that
describes what happened, where it happened, etc. See more.
Metadata
A name/value pair added to telemetry data. OpenTelemetry calls this
Attributes on Spans, Labels on
Metrics and Fields on Logs.
Metric
Records a data point, either raw measurements or predefined aggregation, as
time series with Metadata. See more.
OC
Short form for OpenCensus.
OpenCensus
A set of libraries for various languages that allow you to collect application metrics and distributed traces, then transfer the data to a backend of your choice in real time. Precursor to OpenTelemetry. See more.
OpenTracing
Vendor-neutral APIs and instrumentation for distributed tracing. Precursor to OpenTelemetry. See more.
OT
Short form for OpenTracing.
OTel
Short form for OpenTelemetry.
OTelCol
Short form for OpenTelemetry Collector.
OTLP
Short for OpenTelemetry Protocol.
Processor
Operation performed on data between being received and being exported. For example, batching. Used by ‘Instrumentation Libraries’ and the Collector.
Propagators
Used to serialize and deserialize specific parts of telemetry data such as span
context and Baggage in Spans. See more.
Proto
Language independent interface types. See more.
Receiver
Term used by the Collector to
define how telemetry data is received. Receivers can be push- or pull-based. See
more.
Request
See Distributed Tracing.
Resource
Captures information about the entity for which telemetry is recorded. For
example, a process producing telemetry that is running in a container on
Kubernetes has a pod name, it is in a namespace and possibly is part of a
deployment which also has a name. All three of these attributes can be included
in the Resource and applied to any data source.
REST
Short for Representational State Transfer.
RPC
Short for Remote Procedure Call.
Sampling
A mechanism to control the amount of data exported. Most commonly used with the
Tracing Data Source. See more.
SDK
Short for Software Development Kit. Refers to a telemetry SDK that denotes a
Library that implement the OpenTelemetry API.
Semantic Conventions
Defines standard names and values of Metadata in order to provide
vendor-agnostic telemetry data.
Service
A component of an Application. Multiple instances of a
Service are typically deployed for high availability and
scalability. A Service may be deployed in multiple locations.
Signal
One of Traces, Metrics or Logs. More on
Signals here.
Span
Represents a single operation within a Trace. See more.
Span Link
A span link is a link between causally-related spans. For details see Links between spans and Specifying Links.
Specification
Describes the cross-language requirements and expectations for all implementations. See more.
Status
The result of the operation. Typically used to indicate whether an error occurred. See more.
Tag
See Metadata.
Trace
A DAG of Spans, where the edges between Spans
are defined as parent/child. relationship. See more.
Tracer
Responsible for creating Spans. See more.
Transaction
See Distributed Tracing.
zPages
An in-process alternative to external exporters. When included, they collect and aggregate tracing and metrics information in the background; this data is served on web pages when requested. See more.