Note: In this post, we assume familiarity with some Solana-specific terms. If you're unfamiliar, check out, Solana Fees, Part 1: Solana's Fee Mechanism for a helpful glossary.
Introduction: why aren't my transactions included?
A Solana transaction's journey from user submission to block inclusion can be arduous. Even once the transaction reaches the current leader, it must compete with other transactions for limited blockspace. Including transactions in a purely first-come-first-served fashion encourages spam and may block high-value transactions from ordinary users. To solve this problem we need a fee mechanism.
Priority fees to the rescue?
Priority fees solve this problem, right? Unfortunately, not for most users.