# Basics

Eth1, or simply Ethereum, is a Proof-of-Work blockchain system that first went into production in 2014. We care about Eth1 for several reasons. Eth1 was the first project to employ many design decisions now standard in many other blockchain systems. These influences carry over to Eth2, the primary subject of this text. Many choices made in the construction of Eth2 are a direct or indirect result of lessons learned from observations of Eth1. It's therefore valuable to understand the core components of Eth1 in order to achieve a greater understanding of Eth2.

We've already explored the concept of Proof-of-Work in quite some detail in the previous chapter. This chapter instead focuses on the execution layer of Eth1. We examine carefully the manner in which state and changes to that state are represented in Eth1. We explicitly dissect the structure of Eth1 state, transactions, and blocks. We additionally analyze the mechanism that allows Eth1 to host much more complex applications than its predecessors. Finally, we build an understanding of the hurdles Eth1 faces to achieve long-term growth.

TODO

TODO: This became more of an introductory section. Doesn't make much sense to go into more detail here. Probably want to turn this into a "real" introduction.