Glossary

Review the definitions for terms used across Cloudflare’s Workers documentation.

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Term	Definition
Auxiliary Worker	A Worker created locally via the Workers Vitest integration that runs in a separate isolate to the test runner, with a different global scope.
binding	Bindings allow your Workers to interact with resources on the Cloudflare Developer Platform.
C3	C3 is a command-line tool designed to help you set up and deploy new applications to Cloudflare.
CPU time	CPU time is the amount of time the central processing unit (CPU) actually spends doing work, during a given request.
Cron Triggers	Cron Triggers allow users to map a cron expression to a Worker using a `scheduled()` handler that enables Workers to be executed on a schedule.
D1	D1 is Cloudflare’s native serverless database.
Durable Objects	Durable Objects is a globally distributed coordination API with strongly consistent storage.
duration	Duration is a measurement of wall-clock time — the total amount of time from the start to end of an invocation of a Worker.
environment	Environments allow you to deploy the same Worker application with different configuration for each environment. Only available for use with `wrangler.toml`.
environment variable	Environment variables are a type of binding that allow you to attach text strings or JSON values to your Worker.
handler	Handlers are methods on Workers that can receive and process external inputs, and can be invoked from outside your Worker.
isolate	Isolates are lightweight contexts that provide your code with variables it can access and a safe environment to be executed within.
KV	Workers KV is Cloudflare’s key-value data storage.
module Worker	Refers to a Worker written in module syntax.
origin	Origin generally refers to the web server behind Cloudflare where your application is hosted.
Pages	Cloudflare Pages is Cloudflare’s product offering for building and deploying full-stack applications.
Queues	Queues integrates with Cloudflare Workers and enables you to build applications that can guarantee delivery.
R2	R2 is an S3-compatible distributed object storage designed to eliminate the obstacles of sharing data across clouds.
rollback	Rollbacks are a way to deploy an older deployment to the Cloudflare global network.
secret	Secrets are a type of binding that allow you to attach encrypted text values to your Worker.
service Worker	Refers to a Worker written in service worker syntax.
subrequest	A subrequest is any request that a Worker makes to either Internet resources using the Fetch API or requests to other Cloudflare services like R2, KV, or D1.
Tail Worker	A Tail Worker receives information about the execution of other Workers (known as producer Workers), such as HTTP statuses, data passed to `console.log()` or uncaught exceptions.
V8	Chrome V8 is a JavaScript engine, which means that it executes JavaScript code.
wall-clock time	Wall-clock time is the total amount of time from the start to end of an invocation of a Worker.
workerd	`workerd` is a JavaScript / Wasm server runtime based on the same code that powers Cloudflare Workers.
Wrangler	Wrangler is the Cloudflare Developer Platform command-line interface (CLI) that allows you to manage projects, such as Workers, created from the Cloudflare Developer Platform product offering.
wrangler.toml	The configuration file used to customize the development and deployment setup for a Worker or a Pages Function.