API (Application Programming Interface). An interface to an application which allows other applications to communicate with it. Essentials creates an API out of your site configuration so the site's viewers can interact with the configuration. See also. REST API.

Authentication. When Essentials is secured and a user launches a viewer, the user must sign in. Essentials uses the credentials the user enters to ensure they are a recognized user (the authentication step), and that they have permission to use the site (the authorization step).

Authorization. When a user launches a viewer and Essentials is secured, the user must sign in. Essentials uses the credentials the user enters to ensure they are a recognized user (the authentication step), and that they have permission to use the site (the authorization step).

ArcGIS Server. Software that makes it possible to create GIS services over the web for web mapping applications.

Cluster. A group of computers that work together to behave like a single system. An Essentials deployment with multiple Essentials servers is a cluster. Each server in a cluster uses the same server-side configuration (sites) and client-side web applications (viewers).

Endpoint. See REST Endpoint.

Firewall. A network security system that controls incoming and outgoing network traffic.

Framework. Software that provides generic functionality, which you can customize for different applications. For example, the HTML5 Viewer framework enables you to add HTML5 viewers that are customizable.

GIS (Geographic Information System). A system that captures, analyzes, or manages data that is linked to a location on a map.

Host Name. A human-readable name that stands for an IP address. For example, and are host names.

IP Address (Internet Protocol Address). A numeric label that uniquely identifies a computer or other device connected to a network that uses Internet Protocol. For example, is an IP address. See also: Host Name.

Layer. The data in web maps is usually represented in layers, for example roads would be on a separate layer from rivers and waterways and political boundaries would be on a separate layer from national parks. A Group Layer is group of several layers that look and behave like a single layer.

Map. In the context of Geocortex Essentials, maps are web-based. Web-based maps are fundamentally different from paper-based maps in that they are both interactive and searchable. Web-based maps contain data in many forms, which can be searched and annotated.

Map Service. Map services render maps that can be displayed and queried by mapping applications. Map images are rendered on the server and served to the client. Dynamic map services render map images on demand. Tiled (cached) map services pre-render map images at specific scales and cache the images ("tiles").Essentials supports both dynamic and tiled map services.

Origin. The protocol, host, and port that defines how a web resource is accessed. For example, if you have a viewer that is deployed to and you use SSL and the default port, then the viewer's origin is

Registration. The act of setting up access. For example, in order for Essentials to be able to access your private ArcGIS Online content, you must register Essentials with ArcGIS Online. Minimally, registration information includes the URL to access. It may also include security information such as a user name and password.

REST (Representational State Transfer). An architectural style used for network applications. Communication between the Essentials server, viewers, and ArcGIS Server is done using REST.

REST API. A web-based, REST-compatible representation of the configuration of one or more web mapping applications. The REST API is organized as a hierarchy (a tree). Each site in an Essentials installation has a branch in the hierarchy that represents the configuration of that site. Viewers obtain configuration information by making HTTP requests to the REST API.

REST Endpoint. The items in a REST API's hierarchy are called "endpoints". Each endpoint represents the configuration of a particular resource or operation in the site. Each endpoint has a unique URL, which enables viewers to identify individual endpoints.

Service. In the context of web mapping, services are GIS resources that are located on a server and accessed over a network. Types of service include map services, feature services, and geocoding services.

Site. A technology-neutral configuration of a GIS application. A site's configuration is stored in XML format. Each site has its own configuration file called Site.xml.

Tree. A hierarchy, called a "tree" because it looks like an upside-down tree when represented graphically. The items in a tree are called "nodes". In a REST API, the nodes are called "endpoints". See also: REST Endpoint.

Example of a tree structure in Manager

URI (Uniform Resource Identifier). A string that identifies a resource on a computer or computer network. URIs enable interactions over the Internet using protocols.

URL (Uniform Resource Locator). A type of URI. Commonly known as a web address.

Viewer. In the context of Geocortex Essentials, viewers are the web applications that end users run to interact with a site and its map.