Skim through the following sections. You can always come back to them.

B. Instructions

Instructions in Solana are bundled within a transaction and are executed sequentially.

Each instruction contains a program ID, accounts that it wishes to interact with, and a data field.

1. The program ID specifies the on-chain program (smart contract) that will process the instruction. The accounts array includes all accounts that the instruction will read from or write to. The accounts array must include at least one signer who authorizes the instruction.
2. The data field is an arbitrary byte array that is passed to the program for processing. 

In Solana, the combination of transactions and instructions allows for high throughput and efficient processing.

The network is capable of processing thousands of transactions per second, each containing multiple instructions, which can interact with different programs and accounts.

This design is a key part of Solana's scalability and speed.