What is a blockchain?
A blockchain is a public database that is updated and shared across many computers in a network. “Block” refers to data and state being stored in consecutive groups known as “blocks”. If you send Parallax coins to someone, the transaction data needs to be added to a block to be successful. “Chain” refers to the fact that each block cryptographically references its parent. In other words, blocks get chained together. The data in a block cannot change without changing all subsequent blocks, which would require the consensus of the entire network. Every computer in the network must agree upon each new block and the chain as a whole. These computers are known as “nodes”. Nodes ensure everyone interacting with the blockchain has the same data. To accomplish this distributed agreement, blockchains need a consensus mechanism. If you would like to see how blockchain data is hashed and subsequently appended to the history of block references, be sure to check out this demo↗ by Anders Brownworth and watch the accompanying video below. Watch Anders explain hashes in blockchains:What is Parallax?
Parallax is a blockchain with a computer embedded in it, based in the Geth (Go) implementation of the Ethereum protocol. It is the foundation for building apps and organizations in a decentralized, permission-less, censorship-resistant way. Parallax supports most of the development tooling, third-party wallets and softwares made for Ethereum. In the Parallax universe, there is a single, canonical computer (called the Parallax Virtual Machine, or PVM) whose state everyone on the Parallax network agrees on. Everyone who participates in the Parallax network (every Parallax node) keeps a copy of the state of this computer. Additionally, any participant can broadcast a request for this computer to perform arbitrary computation. Whenever such a request is broadcast, other participants on the network verify, validate, and carry out (“execute”) the computation. This execution causes a state change in the PVM, which is committed and propagated throughout the entire network. Requests for computation are called transaction requests; the record of all transactions and the PVM’s present state gets stored on the blockchain, which in turn is stored and agreed upon by all nodes. Cryptographic mechanisms ensure that once transactions are verified as valid and added to the blockchain, they can’t be tampered with later. The same mechanisms also ensure that all transactions are signed and executed with appropriate “permissions” (no one should be able to send digital assets from Alice’s account, except for Alice herself).What is LAX?
Lax is the native cryptocurrency of Parallax. The purpose of Laxes is to allow for a market for computation. Such a market provides an economic incentive for participants to verify and execute transaction requests and provide computational resources to the network. Any participant who broadcasts a transaction request must also offer an amount of LAX to the network as a bounty. The network will award this bounty to whoever eventually does the work of verifying the transaction, executing it, committing it to the blockchain, and broadcasting it to the network. The amount of Laxes paid corresponds to the resources required to do the computation. These bounties also prevent malicious participants from intentionally clogging the network by requesting the execution of infinite computation or other resource-intensive scripts, as these participants must pay for computation resources.What are Smart Contracts?
In practice, participants don’t write new code every time they want to request a computation on the PVM. Rather, application developers upload programs (reusable snippets of code) into PVM state, and users make requests to execute these code snippets with varying parameters. We call the programs uploaded to and executed by the network smart contracts. At a very basic level, you can think of a smart contract like a sort of vending machine: a script that, when called with certain parameters, performs some actions or computation if certain conditions are satisfied. For example, a simple vendor smart contract could create and assign ownership of a digital asset if the caller sends Laxes to a specific recipient. Any developer can create a smart contract and make it public to the network, using the blockchain as its data layer, for a fee paid to the network. Any user can then call the smart contract to execute its code, again for a fee paid to the network. Thus, with smart contracts, developers can build and deploy arbitrarily complex user-facing apps and services such as: marketplaces, financial instruments, games, etc.Terminology
Blockchain
The sequence of all blocks that have been committed to the Parallax network in the history of the network. So named because each block contains a reference to the previous block, which helps maintain an ordering over all blocks (and thus over the precise history).LAX
LAX (or plural laxes) is the native cryptocurrency of Parallax. Users pay Laxes to other users to have their code execution requests fulfilled. More on LAXPVM
The Parallax Virtual Machine is the global virtual computer whose state every participant on the Parallax network stores and agrees on. Any participant can request the execution of arbitrary code on the PVM; code execution changes the state of the PVM. More on the PVMNodes
The real-life machines which are storing the PVM state. Nodes communicate with each other to propagate information about the PVM state and new state changes. Any user can also request the execution of code by broadcasting a code execution request from a node. The Parallax network itself is the aggregate of all Parallax nodes and their communications. More on nodesAccounts
Where Laxes are stored. Users can initialize accounts, deposit Laxes into the accounts, and transfer Laxes from their accounts to other users. Accounts and account balances are stored in a big table in the PVM; they are a part of the overall PVM state. More on accountsTransactions
A “transaction request” is the formal term for a request for code execution on the PVM, and a “transaction” is a fulfilled transaction request and the associated change in the PVM state. Any user can broadcast a transaction request to the network from a node. For the transaction request to affect the agreed-upon PVM state, it must be validated, executed, and “committed to the network” by another node. Execution of any code causes a state change in the PVM; upon commitment, this state change is broadcast to all nodes in the network. Some examples of transactions:- Send 1 lax from my account to Alice’s account.
- Publish some smart contract code into the PVM state.
- Execute the code of the smart contract at address X in the PVM, with arguments Y.