> For the complete documentation index, see [llms.txt](https://docs.applayer.com/testnet/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.applayer.com/testnet/glossary.md).

# Glossary

| Term                    | Meaning                                                                                                                                                             |
| ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| EVM                     | Ethereum Virtual Machine                                                                                                                                            |
| DeFi                    | Decentralized Finance                                                                                                                                               |
| DB                      | Database                                                                                                                                                            |
| rdPoS                   | Random Deterministic Proof-of-Stake                                                                                                                                 |
| RLP                     | Recursive-Length Prefix                                                                                                                                             |
| BDK                     | Blockchain Development Kit                                                                                                                                          |
| NFT                     | Non-Fungible Token                                                                                                                                                  |
| RPC                     | Remote Procedure Call                                                                                                                                               |
| UTXO                    | Unspent Transaction Output (commonly used by Bitcoin-derived chains, analogous to Accounts, used by Ethereum-derived chains)                                        |
| Secp256k1               | The elliptic curve used for Bitcoin’s public key cryptography                                                                                                       |
| Token table             | A record of the token balances on each subnet, held by AppLayerLabs                                                                                                 |
| Block race condition    | A situation where multiple blocks compete for the position of the next block in the chain                                                                           |
| Block congestion system | A component that manages the registration of blocks in the blockchain                                                                                               |
| RNG                     | Random Number Generator, a component in charge of making validator selection unpredictable                                                                          |
| Master address          | The address that adds validators to the network in a centralized implementation                                                                                     |
| Transpiler              | A program that converts source code written in a specific programming language into its equivalent in another language                                              |
| Constructor             | A function that initializes the state variables of a contract                                                                                                       |
| Pointer                 | An item that shows where data is stored and helps verify it                                                                                                         |
| Sandbox                 | An isolated testing environment for experimenting with code                                                                                                         |
| Merkle tree             | An abstract data type with leaves (nodes) holding cryptographic hashes of data blocks while nodes that aren’t leaves have cryptographic hashes of their child nodes |