This page provides brief definitions and links to more information of terms
that are used in the Cloud Endpoints documentation.

API key
:   A code passed in by a client application when it calls an API. API
    keys identify the application or the Google Cloud project making
    the call to the API. See
    [Why and when to use API keys](https://docs.cloud.google.com/endpoints/docs/openapi/when-why-api-key.md.txt)
    for more information on using an API key with your Endpoints API.

Auth0
:   A service that lets you define how users authenticate to applications. See
    [Auth0](https://auth0.com) for more information.

Cloud Endpoints Frameworks
:   Endpoints Frameworks for the App Engine standard environment
    consists of tools, libraries, and capabilities that let you generate APIs and
    client libraries from an App Engine application. See
    [About Endpoints Frameworks](https://docs.cloud.google.com/endpoints/docs/frameworks/java/about-cloud-endpoints-frameworks.md.txt)
    for more information.

container
:   A software package that contains the libraries, frameworks, and settings.
    that an application requires to run. See
    [What is a container](https://www.docker.com/what-container)
    for more information.

CORS
:   Cross-Origin Resource Sharing (CORS) is a specification that provides a way
    for web applications to access resources on a server in another domain
    (technically, in another origin). To learn more about CORS, see the
    [Mozilla Developer Network (MDN) web docs](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS)
    and the [Fetch Living Standard](https://fetch.spec.whatwg.org/).

Docker
:   Open source software that lets you automate deploying applications inside
    software containers. See [What is Docker](https://www.docker.com/what-docker)
    for more information.

Extensible Service Proxy
:   The Extensible Service Proxy (ESP) is an Nginx-based high-performance, scalable proxy
    that runs in front of an OpenAPI or gRPC API backend and provides API management
    features such as authentication, monitoring, and logging. See
    [About Endpoints](https://docs.cloud.google.com/endpoints/docs/openapi/about-cloud-endpoints.md.txt)
    and
    [Endpoints: Architectural overview](https://docs.cloud.google.com/endpoints/docs/openapi/architecture-overview.md.txt)
    for more information.

Extensible Service Proxy V2

:   The Extensible Service Proxy V2 (ESPv2) is an [Envoy](https://www.envoyproxy.io/docs/envoy/latest/)-based
    high-performance, scalable proxy that runs in front of an OpenAPI or gRPC API backend and provides API management
    features such as authentication, monitoring, and logging. See
    [About Endpoints](https://docs.cloud.google.com/endpoints/docs/openapi/about-cloud-endpoints.md.txt)
    and
    [Endpoints: Architectural overview](https://docs.cloud.google.com/endpoints/docs/openapi/architecture-overview.md.txt)
    for more information.

:   ESPv2 supports version 2 of the
    [OpenAPI Specification](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md) and [gRPC](http://www.grpc.io) Specifications.

Firebase authentication

:   Google's authentication service that supports end user sign-in for client
    applications by using credentials from popular federated identity providers
    such as Google, Facebook, or Twitter. See
    [Firebase authentication](https://firebase.google.com/docs/auth/)
    for more information.

Google ID token

:   A JSON Web Token (JWT) that contains the [OpenID
    Connect](https://developers.google.com/identity/protocols/OpenIDConnect)
    fields needed to identify a Google user account or service account, and that
    is signed by Google's authentication service, `https://accounts.google.com`.

gRPC

:   A high performance, open source universal RPC framework developed by Google.
    In gRPC, a client application can directly call methods on a server application
    on a different machine as if it was a local object. See
    [Cloud Endpoints for gRPC APIs](https://docs.cloud.google.com/endpoints/docs/grpc/about-grpc.md.txt)
    for information on using gRPC with Endpoints and the
    [gRPC](http://www.grpc.io)
    website for general information.

JWT

:   JSON Web Token is an open standard access token format for use in HTTP
    Authorization headers and URI query parameters. See
    [Introduction to JSON Web Tokens](https://jwt.io/introduction/) for general
    information.

kubectl

:   A command-line interface for running commands against Kubernetes clusters. You
    use `kubectl` when deploying an API for Endpoints on a Kubernetes
    or
    [Google Kubernetes Engine](https://docs.cloud.google.com/kubernetes-engine/docs/clusters)
    cluster.
    See [Overview of `kubectl`](https://kubernetes.io/docs/user-guide/kubectl-overview/)
    for more information.

Kubernetes

:   Open source software that lets you automate the deployment, management,
    and scaling of containerized applications across clusters of hosts.
    See [Kubernetes](https://kubernetes.io/) for more information.

NGINX

:   An open source, high-performance HTTP server and service proxy that
    ESP is based on. See the
    [NGINX Wiki](https://www.nginx.com/resources/wiki/)
    for more information. For information on ESP, see
    [About Cloud Endpoints](https://docs.cloud.google.com/endpoints/docs/openapi/about-cloud-endpoints.md.txt)
    and [Endpoints: Architectural overview](https://docs.cloud.google.com/endpoints/docs/openapi/architecture-overview.md.txt).

OpenAPI

:   The [Open API Initiative](http://openapis.org) is an industry-wide effort to
    standardize the description of REST APIs. APIs that are described with the
    [OpenAPI Specification](https://github.com/OAI/OpenAPI-Specification) (formerly
    the [Swagger Specification](http://swagger.io)) can be supported with common
    tools that create documentation, automate testing, and generate code for clients
    and servers. See
    [OpenAPI overview](https://docs.cloud.google.com/endpoints/docs/openapi/openapi-overview.md.txt)
    for more information.

OpenAPI document

:   A configuration file in either YAML or JSON format that you use to describe
    your API.

surface

:   The public interface of an API. An API's surface consists of the methods
    as well as the parameters and return types used in the methods.