What is Solana’s Programmability?

For starters, smart contracts in Solana are called programs and are stateless. This means that, unlike Ethereum smart contracts which contain both the program logic and state, Solana programs contain only the logic and are deployed on-chain in a ‘read-only’ mode. Once deployed, the programs can be accessed by external accounts, which contain the data related to program interaction (unlike Ethereum accounts, accounts on Solana can store data). This separation of logic and state informs the specific production flow of Solana dApps.

Every Solana dApp consists of two parts: a blockchain-based program (or set of programs) and a web application through which users can interact with the blockchain code. The blockchain program is deployed directly to a Solana cluster and users can then send instructions to the program via transactions. A single transaction can contain one or several instructions, which are then executed sequentially and atomically. If all instructions are valid, the program is successfully executed. However, if even a single instruction is invalid, the changes made by the transaction are discarded.