Smart contracts
A smart contract is a computer program that controls the transfer of assets to different parties. It defines the rules and penalties of the agreement. They can be used for a number of things such as token creation, decentralized autonomous organizations, crowdsales and more.
DAO
A decentralized autonomous organization (DAO) is a type of smart contract that acts like a business or organization. Token owners are like voting members. They can make proposals on what to do with funds, add/ remove members, propose new rules or change old ones and more.
Crowdsale
A Ethereum crowdsale contract manages funds and determines how to the funds will be spent after the money is raised to help fight mismanagement. They are often used with a DAO to determine how the money is spent.