---
title: Core
description: Core blockchain primitives and data structures for the Thru blockchain
source_url:
  html: https://thru.org/docs/spec/core/overview/
  md: https://thru.org/docs/spec/core/overview.md
---

# Core

The Thru Core specification defines the fundamental data structures and primitives that form the foundation of the Thru blockchain. These components handle the basic building blocks of blockchain operations.

## Key Components

### [Transactions](https://thru.org/docs/spec/core/transactions.md)

Atomic units of computation with detailed binary format specification. Includes transaction headers with fee payer and program information, account address lists (read-write and read-only), instruction data, and optional state proofs for fee payer accounts. Defines transaction validation criteria, signature verification, and account list ordering requirements.

### [Thru Format (thrufmt)](https://thru.org/docs/spec/core/thru-fmt.md)

Standard human-readable encoding format for Thru public addresses (`ta…`) and signatures (`ts…`). Documents the base64url encoding scheme, checksum algorithms, and CLI tools for converting between raw hex and the canonical string form. All clients must match the encoding behavior exactly, byte-for-byte.