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Blockchain data carries assumptions that are obvious to crypto-native engineers and invisible to everyone else: blocks can be un-mined, a “token” means five different things depending on the chain, and a trade can be a pool swap or a resting limit order. These pages explain the concepts you need to read Allium’s data correctly, and state what Allium actually does about each one — how deep we wait before calling a block confirmed, how we correct reorged records, and which tables represent which onchain primitive. Start here if you are new to onchain data. If you already know the concepts and want schemas, go straight to the Data Catalog or the Realtime API.

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Blockchain fundamentals

Consensus mechanisms

How chains agree on a single history, and why that shapes the data you get

Rollups and L2s

What a layer 2 is, what a sequencer does, and the data quirks that follow

Transaction finality

When a transaction is irreversible, and Allium’s confirmation depth per chain

Reorgs

What happens when a chain discards blocks, and how Allium corrects for it

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Tokens and wallets

Fungible vs non-fungible

The difference between interchangeable and unique assets

Token standards

ERC-20, ERC-721, SPL, Token-2022, and why the differences matter for data

Hot vs cold wallets

Custody models, and what each looks like onchain

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Trading and DeFi

AMMs vs CLOBs

Two ways to match trades onchain, and the two shapes of data they produce

Perpetuals

Funding rates, leverage, liquidations, and the tables that track them

Oracles

How offchain prices reach onchain contracts, and how Allium prices assets

MEV

Why transaction ordering has value, and how it distorts naive metrics

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Need something else?

These pages cover concepts, not schemas. For table-level reference see the Data Catalog; for endpoint reference see the Realtime API. If a concept you need explained is missing, email [email protected].