# Glossary

<table><thead><tr><th width="216.8363932348065">Terms</th><th width="455.8958094609532">Definition</th></tr></thead><tbody><tr><td>API key</td><td>A simple encrypted string generated by users and verified by BlockPI Hub. It is a pass to use the BlockPI Network service.</td></tr><tr><td>Auto-Renew</td><td>Setting of the following automatic purchase strategy when the current RU packages are fully consumed.</td></tr><tr><td>BlockPI Hub</td><td>BlockPI servers which manage the user system, node rating and authenticator system, and accounting system.</td></tr><tr><td>BlockPI Node Balancer</td><td>An algorithm BlockPI developed that governs how Gateways dispatch requests to HyperNodes.</td></tr><tr><td>BlockPI Testnet</td><td>A BlockPI Testnet is a network constructed for testing purposes. It consists of multiple instances such as Testnet #1, #2, and so on. Testnet #1 has completed in September 2022. Typically, a Testnet provides incentives and is open to third-party operators and users.</td></tr><tr><td>Gateway</td><td>Distributed nodes which collect and sort users' requests, and route them to the proper HyperNodes.</td></tr><tr><td>Node Client</td><td>End nodes that process RPC requests and send the response back to the users.</td></tr><tr><td>Pay As You Go</td><td>An option in Auto-Renew. Directly deduction of the wallet balance for extra RU use if the wallet balance is greater than $0 and the RU balance is 0.</td></tr><tr><td>IPFS</td><td>A distributed system for storing and accessing files, websites, applications, and data.</td></tr><tr><td>Public User</td><td>Unregistered users who use BlockPI public endpoints for free.</td></tr><tr><td>Registered User</td><td>Users who registered are able to generate API keys and enjoy advanced services.</td></tr><tr><td>Request Unit (RU)</td><td>The basic unit used to calculate the users' usage for sending RPC requests.</td></tr><tr><td>RU Package</td><td>An RU package contains a certain amount of RUs. Different RU packages come with varying numbers of RUs and expiration dates.</td></tr></tbody></table>