Pro Investor Academy
LESSON 4.3
5 min learning time

Smart Contracts and Crypto Networks

Ethereum is a programmable blockchain where applications run as smart contracts.

Learning objectives

  • Explain Ethereum as a blockchain that runs programs (smart contracts)
  • Recognize what gets built on it
  • Identify the extra risks programmability adds

Programmable settlement

Ethereum extends the ledger idea by allowing code — smart contracts — to run on the network. A contract does nothing on its own: it runs when a transaction calls it, and then executes its code exactly as written, without an intermediary.

Contracts cannot see the outside world. Anything like a price or an exchange rate has to be supplied by an oracle — a service that posts outside data on-chain. If the oracle is wrong or manipulated, the contract acts on wrong data.

Ether (ETH) is the asset used to pay for that computation, in fees commonly called gas.

What gets built on it

Lending protocols, exchanges, stablecoins, tokens and collectibles. This ecosystem has produced both genuine engineering and enormous amounts of fraud.

Extra risks

Smart contracts can contain bugs. Code that holds funds has been exploited many times, and there is often no recourse when it happens. Oracle failures and admin keys that can change a contract are further risks.

Key concepts

Select a term to read its definition.

  • Ethereum

    A programmable blockchain on which applications run as smart contracts.

    View in the glossary
  • Smart contract

    Code on a blockchain that executes automatically when its conditions are met.

    View in the glossary
  • Gas

    The fee paid to execute a transaction or smart contract on Ethereum.

    View in the glossary
  • Stablecoin

    A crypto token designed to hold a steady value, usually against a currency such as the U.S. dollar.

    View in the glossary
See the full glossary

Why this matters

Understanding smart-contract risk explains why 'the code is audited' is not a guarantee.

Check your understanding

No score is recorded. This is only here to test whether the lesson landed.

1. What is a smart contract?
2. Hypothetical: a lending protocol advertises an 18% yield and says its smart contract was audited last year. You are thinking of depositing $2,000. Which step best addresses the code risk this lesson describes?
3. A lending protocol built on smart contracts offers an unusually high yield. What extra layer of risk does this lesson highlight, beyond ordinary price volatility?

0 of 3 answered. Answer every question to see the answers.

Key takeaways

  • Ethereum settles transactions and runs smart contracts.
  • Applications built on it inherit its risks and add their own.
  • Code flaws and external-data failures can cause losses even when the network works.
Written by
Pro Investor Academy Research Team
Content type
Educational article
Published
2026-09-13
Last reviewed
2026-09-13

Sources

Bitcoin and Digital ScarcityTokenomics

Educational content only. This lesson is not investment, tax or legal advice and does not recommend buying or selling any specific investment. All investing involves the risk of loss.