> ## Documentation Index > Fetch the complete documentation index at: https://docs.epay123.net/llms.txt > Use this file to discover all available pages before exploring further. # Glossary Definitions of key terms used in the documentation. | Term | English Full Name/Abbreviation | Explanation | | :---------------------------: | :-------------------------------- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Blockchain** | Blockchain | A decentralized, distributed digital ledger technology that records transaction data in chronologically linked blocks, ensuring it is immutable and transparent. | | **Cryptocurrency** | Cryptocurrency | A digital or virtual currency created using cryptography and blockchain technology, used as a medium of exchange, such as Bitcoin (BTC) and Ethereum (ETH). | | **Stablecoin** | Stablecoin | A type of cryptocurrency whose value is pegged to a fiat currency (like the US dollar or Euro) or other stable assets, designed to reduce price volatility, such as USDT and USDC. | | **Smart Contract** | Smart Contract | A self-executing contract stored on a blockchain, where the terms of the agreement are automatically executed when preset conditions are met, without the need for intermediaries. | | **Fiat Currency** | Fiat Currency | A currency issued by a government that is not backed by a physical commodity (like gold), with its value based on credit and legal decree, such as the Chinese Yuan (CNY) and the US Dollar (USD). | | **Merchant** | Merchant | A business or individual that accepts cryptocurrency or stablecoins as payment for their goods or services. | | **API** | Application Programming Interface | An Application Programming Interface that allows different software systems to communicate with each other. The payment platform provides APIs to allow merchants' systems to call functions like payment and inquiry. | | **Key/Secret** | API Key & Secret | A pair of keys generated by the platform for a merchant, used for identity authentication and API request signing. The Key is a public identifier, while the Secret is a private key that must be kept confidential. | | **Webhook** | Webhook | An HTTP callback (or API) triggered by an event. The payment platform uses Webhooks to proactively send real-time notifications to the merchant's server, such as payment status updates. | | **Callback URL** | Callback URL | A URL provided by the merchant and pre-configured on the platform to receive Webhook notifications. | | **Gas Fee** | Gas Fee | The computational fee required to execute a transaction or smart contract on a blockchain network, typically paid in the native token of that blockchain (such as ETH). | | **Transaction Hash** | Transaction Hash/Txid | An alphanumeric string that uniquely identifies a transaction on the blockchain, used for querying and verifying transaction details. | | **Block Confirmation** | Block Confirmation | Refers to the number of new blocks that have been added to the blockchain after a transaction has been included in a block. The more confirmations, the lower the probability of the transaction being reversed, and the higher the security. | | **Settlement** | Settlement | The process of crediting the successfully received payment amount to the merchant's account balance after deducting service fees. | | **Withdrawal** | Withdrawal | The process of transferring the cryptocurrency balance from the platform account to an external blockchain address. | | **OTC** | Over-The-Counter | Over-The-Counter trading. An internal matching service provided by the platform that allows users (merchants) to buy and sell large amounts of cryptocurrency directly with other users at a negotiated price, avoiding slippage. | | **KYC** | Know Your Customer | Know Your Customer. A regulatory identity verification process where the platform must collect and verify user (merchant) identity information to prevent fraud and illegal activities. | | **AML** | Anti-Money Laundering | Anti-Money Laundering. A set of laws, regulations, and procedures designed to prevent the concealment of the source of illegally obtained funds through the financial system. | | **Cold Wallet** | Cold Wallet | An offline wallet for storing cryptocurrencies where the private keys never touch the internet, providing very high security, typically used for storing large amounts of funds. | | **Hot Wallet** | Hot Wallet | An online wallet connected to the internet, facilitating quick deposits and withdrawals, but with lower security compared to a cold wallet. | | **Exchange Rate Fluctuation** | Exchange Rate Fluctuation | The price volatility of a cryptocurrency relative to fiat currencies or other cryptocurrencies. Payment platforms usually offer a price-locking feature for merchants to mitigate this risk. | | **Finality** | Finality | The state on a blockchain where a transaction, once confirmed, is irreversible and cannot be altered. Different blockchains have different finality times. |