In the following lessons, we'll dive into the essentials of Solana Smart Contracts, covering everything from transactions and instructions to accounts and the Program Derived Addresses (PDAs). 

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

We will go through four main concepts:

A. Transactions

B. Instructions

C. Accounts

D. Program Derived Addresses (PDAs)

Let's begin! 🔥

A. Transactions

In Solana, a transaction is a signed instruction sequence that is executed atomically. Transactions are used to interact with programs (smart contracts) deployed on the Solana network.

A transaction contains one or more instructions, a recent blockhash, and signatures.

1. The recent blockhash, also known as a transaction "recentBlockhash", is used for transaction processing and lifespan. 
2. The signatures are the cryptographic proof of the transaction's integrity and authority. Each transaction must be signed by the appropriate account holders as per the instructions contained within.