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.