This glossary covers Elasticsearch Service. If a term is not in this list, you can also look in the Elasticsearch glossary.

Manages hosts that contain Elasticsearch and Kibana nodes. Controls the lifecycle of these nodes by creating new containers and managing the nodes within these containers when requested. Used to scale the capacity of your Elasticsearch Service installation.
APM Server
A running instance of the application performance monitoring server, which receives data from APM Agents and transforms them into documents stored on the Elasticsearch cluster.
availability zone
Contains resources available to an Elasticsearch Service installation that are isolated from other availability zones to safeguard against failure. Could be a rack, a server zone, or some other logical constraint that creates a failure boundary. In a highly available cluster, the nodes of a cluster are spread across two or three availability zones to ensure that the cluster can survive the failure of an entire availability zone.
cluster, Elasticsearch cluster
One or more Elasticsearch nodes which share the same cluster name.
console, Elasticsearch Service Console
Provides web-based access to manage your Elasticsearch Service deployments.
Includes an instance of Elasticsearch Service software and its dependencies. Used to provision similar environments, to assign a guaranteed share of host resources to nodes, and to simplify operational effort in Elasticsearch Service.
An internal Elasticsearch Service component that logically groups services and acts as a distributed coordination system and resource scheduler.
data center
Check availability zone.
One or more products from the Elastic Stack configured to work together and running on Elasticsearch Service.
deployment template
A deployable, reusable configuration of Elastic products and solutions.
Elastic Cloud, EC
The official hosted Elastic Stack offering, from the makers of Elasticsearch. Available as a software-as-a-service (SaaS) offering on different cloud platforms, such as AWS, GCP, and Microsoft Azure.
Elasticsearch Service, ECE
The official enterprise offering host and manage the Elastic Stack yourself at scale. Can be installed on a public cloud platform, such as AWS, GCP or Microsoft Azure, on your own private cloud, or on bare metal.
Elastic Stack
Also known as the ELK Stack, the Elastic Stack is the combination of various Elastic products that integrate for a scalable and flexible way to manage your data.
hardware profile
A built-in template that supports a specific use case for the Elastic Stack, such as a cluster with a hot-warm architecture.
A product from the Elastic Stack that is running in a deployment, such as an Elasticsearch node or a Kibana instance. When you choose more availability zones, the system automatically creates more instances for you.
instance type
Categories for instances representing an Elastic feature or cluster node types, such as master, ml or data.
The free and open analytics and visualization platform designed to work with Elasticsearch.
machine learning node, ML node
A type of Elasticsearch node that is designed to model the behavior of your Elasticsearch data to detect anomalies.
master node
Responsible for cluster-wide actions, such as creating or deleting an index, tracking which nodes are part of the cluster, and deciding which shards to allocate to which nodes. Improves the resilience of Elasticsearch, but does not handle requests and does not hold any data. Master nodes need fewer CPU and memory resources and less storage than other nodes. Also check node in this glossary and Node in the Elasticsearch documentation.
A running instance of Elasticsearch which belongs to a cluster, typically one per host. Nodes will look to discover an existing cluster by the same name when they start up and try to join that cluster.
no-op (no operation) plan
The application of a rolling update on your deployment without actually applying any configuration changes. This type of update can be useful to resolve certain health warnings. Check Scenario: How do I resolve deployment health warnings?.
Deployments with specialized templates that are pre-configured with sensible defaults and settings for common use cases.
Prevents cases of split brain in distributed clusters, where a cluster splits into multiple, autonomous parts that continue to handle requests independently of each other, at the risk of affecting cluster consistency and data loss. Ensures a quorum-based majority of (n/2)+1 nodes, where n is the number of nodes in the cluster. The minimum number of master nodes to reach quorum in a two-node cluster is the same as for a three-node cluster: two nodes must be available.
vCPU stands for virtual central processing unit. vCPUs are virtual compute units assigned to your nodes. The value is dependent on the size and hardware profile of the instance. The instance may be eligible for vCPU boosting depending on the size.
A coordination service for distributed systems used by Elasticsearch Service to store the state of the installation. Responsible for discovery of hosts, resource allocation, leader election after failure and high priority notifications.