What is a smart contract?
Intelligent Ethernet Square in the contract is a virtual application to run on machines intended. This is a distributed "world computer" with computing power provided by all Ethereum nodes. Any node provides all the computing power of digital goods will Ether / currency as a resource support payment.
They are named smart contracts, because you can write "contracts and ties" that are automatically executed when the requirements are met. Intelligent combined, with code that automates pay, easy, without the need for a trusted third party goods held by money and sign the cross easily.
Smart contracts can be used for many different things. Developers can create smart contracts to provide functions for other smart contracts, similar to how software libraries work. Alternatively, the smart contract can simply be used as an application to store information on the Ethereum blockchain.
In order to actually execute the smart contract code, someone must send enough Ether tokens* as a transaction/transaction fee-how much depends on the required computing resources. This is a cost/price for Ethereum nodes to participate and provide computing power.
Comparison of APP project and DAPP project
APP: Trust comes from the project site, endorsement, packaging, high XJ content
DAPP: No need for platform, endorsement, packaging, trust the smart contract from TRON, face the essence
APP: turn off W at any time
DAPP: Cannot close W
APP: need maintenance, upgrade
DAPP: No maintenance, no upgrade
APP: X requires review/approval
DAPP: No review/check, no manual intervention
APP: H guest attack
DAPP: H client cannot attack
APP: Unfair flow of capital / opaque / clear
DAPP: The flow of capital to the public / open / open
APP: Change mode and system at any time
DAPP: Cannot change the mode system
APP: The code is not public, and the project party has all control/control rights
DAPP: The code is all open source, no one has control/control rights