# 2.2 Core Architecture

<figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXfkwYzO-sFgXAywNnPYQJG7BVFIwCKBjABg6_KXL_5tXQ5SZllhQLBTxU_MQfNSY2x112AWoMWFCwwaAC9badfPsiBot0vpdtZCW-EtgsiXDssIihqLXifLpzOgiEYt9IUa3EzT9-KL60aXr3JaMQ?key=5XZ-nso-X2d5xjt0asyHbOX8" alt=""><figcaption></figcaption></figure>

PEM utilizes a multi-layer architecture, which from top to bottom mainly includes:

* Top Layer Applications : Solidity smart contract language, decentralized applications (DApps), payment transactions.
* API Interface Services : Providing HTTP, TCP-related interface RPC framework services.
* Distributed Ledger : Including transactions, blocks, block verification tools, receipts, state data, and transaction pool-related information.
* Virtual Machine (PVM): The core execution layer for smart contracts.
* Consensus : A hybrid consensus mechanism that combines Proof of Work (PoW) and Byzantine Fault Tolerance (BFT) algorithms.
* Network Services : Peer-to-peer node discovery and connection services, blockchain synchronization services.
* Underlying Services : Database (levelDB, etc.), cryptography (elliptic curve algorithms, etc.), basic algorithms (MPT/Bloom/RLP, etc).