PRE is an [ERC-20](https://coinmarketcap.com/alexandria/glossary/erc-20) token on Ethereum. ERC-20 is a token standard most new tokens follow when publishing on the Ethereum blockchain. Ethereum is one of the most popular blockchains and the go-to solution for many decentralized applications and exchanges to launch on. It is secured by a [proof-of-work ](https://coinmarketcap.com/alexandria/glossary/proof-of-work-pow)consensus mechanism that requires miners to mine new Ether. A set of decentralized nodes validates transactions and secures the Ethereum blockchain.
The platform is secured by nodes, which connect to a Node Gatewaythat receives requests from the server and removes personally identifiable information from the search requests. A node registry manages the identity of all nodes, the node stats and payouts. Nodes are compensated in PRE for different types of services:
1) Registering (all nodes). Registering with a Node Gateway, which can then route queries to the node if it passes health and security validation.
2) Validating (all nodes). Coordinating with a Node Validator to ensure that each node is only running trusted Presearch software (to avoid security issues from potential bad actors).
3) Coordinating. Processing and distributing queries sent by Node Gateways. This may require routing to multiple serving nodes and aggregating the results.
4) Federating. Proxying other data sources and returning their data as part of search results.
5) Serving. Hosting portions of the search index used to process queries.
6) Crawling. Crawling websites to build out search indices.
7) Indexing. Writing federated or crawled data to search indexes to be served by serving nodes.