Network

What is a network?

In the context of information technology, as defined by IONOS:
A network is a group of two or more computers or other electronic devices that are interconnected for the purpose of exchanging data and sharing resources.
In the context of ICON, networks are different ICON environments you can access for development, testing, or production use cases.

What makes a network decentralized?

From the Wikipedia page on decentralization:
Decentralization or decentralisation is the process by which the activities of an organization, particularly those regarding planning and decision making, are distributed or delegated away from a central, authoritative location or group.[1]​
In the context of ICON, the are various groups that maintain computers that all contribute to the state of the network. This is in contrast to a centralized network, Google Cloud, for example, where all computers that contribute the state are owned and operated by the company itself. There are benefits and drawbacks to each approach, however, in order to remain trustless, a blockchain network must be decentralized.

ICON Network structure

The core ICON Network consists of three layers: Users, API Endpoints, and Validator nodes. The latter two topics are discussed in their own sections. Users are explained briefly on this page.
The network can be thought of as hierarchical, with users being the outer-most layer, API Endpoints being the middle layer, and Validator nodes being the internal layer.

Users

A user is defined by the ICON glossary as follows:
Parties that interact with the blockchain. Senders and receivers in a transaction. Token holders. Includes end-users and machine-users
A user is not structurally integral to maintain the blockchain itself. Users are integral, however, to defining the utility of the ICON network. Without users, then the network is not worth anything. With a healthy userbase, the network is worth something in the at-large economy.
As mentioned in the definition, there are two types of users: end-users and machine-users. These are the definitions from the glossary.
End-users:
Person. A type of user that is either a person or a group of people
Machine-users:
Service that connects to another application. A type of user that acts on behalf of an end-user