# About Smart Contracts
Ethereum has what's called "smart contracts" that perform operations on the blockchain according to their programming. However, compared to normal websites or applications they have some unique advantages:
- Once a smart contract exists, it can't be changed, even by its creators.
- The result of the operation is guaranteed by the blockchain to be consistent. In other words, the entire blockchain agrees on a single result.
- Once the operation is done, it can never be altered or erased.
What this means in practice is that if you can verify the source code of the contract, you don't have to trust the creator or anyone else to be able to use it safely.
The most common type of smart contract on Ethereum is the ERC20 Token that specifies a fungible asset that can be sent between accounts.
You can learn more about smart contracts in the Mastering Ethereum free ebook.
You can read more about Blockwell contracts, or select one from the left navigation.