A chain reorganization happens when a blockchain replaces part of its history with an alternative branch. Here's how the mechanism works, what's at risk, and when a reorg becomes an attack.

Probabilistic finality means a transaction becomes statistically harder to reverse over time. Deterministic finality means it cannot be reversed by protocol design. The difference shapes how blockchains are built.

Finality is when a blockchain transaction becomes irreversible. Bitcoin uses probabilistic finality, Ethereum uses economic finality, and BFT chains achieve deterministic finality. Here's how each model works and where the tradeoffs live.

A full node validates the current chain state. An archive node stores every historical state. Here's why that distinction matters for infrastructure, data access, and chain verification.

A light client verifies blockchain data without downloading the full chain — using block headers, Merkle proofs, and cryptographic commitments. Most wallets skip this entirely and trust a centralized RPC instead.

Blockchain state is the current snapshot of everything true on a network — every balance, every contract's stored data. Transactions are instructions that change state. This post explains how state works, why it's growing, and what Ethereum is doing about it.

Data availability is the guarantee that block data can actually be downloaded and verified — not just that a block header exists. This explains the problem, how data availability sampling works, and where the dedicated DA layer landscape stands.

A sequencer is the actor in an L2 rollup that orders, batches, and posts transactions to Ethereum. It's why L2s are fast — and why they're currently more centralized than most users realize.

Account abstraction makes wallet authorization programmable rather than hardcoded. ERC-4337 enables social recovery, gas sponsorship, transaction batching, and session keys — without changing Ethereum's core protocol.

MEV — Maximal Extractable Value — is profit available to block producers who control transaction ordering. This post explains the mechanism, how MEV-Boost reshaped Ethereum block production, and what's changing.

NFT security means two things — protecting the token record (wallet custody) and protecting the media it points to (on-chain vs IPFS vs centralized servers). This post explains both layers and where the real risks actually live.

NFT transfers look simple but the mechanics involve enough layers that small mistakes are permanent. This post covers how transfers actually work on EVM chains, what can go wrong, and what to verify before confirming.