6. If the smart contract author has programmed the SELFDESTRU CT

capability, only then its functionality shall be available.

7 . In case the contract’s code does not have a SELFDESTRU CT opcode

or is inaccessible, it cannot be deleted.

8. Irrespective of the number of contracts you call or what they do when

called, transactions are atomic and execute in their entirety, recording

any changes in the global state if all execution terminates successfully.

9 . The program executed without an error and reached its execution end

is the meaning of successful termination.

10. Due to an error occurring, if execution fails, all of its effects are

“rolled back” as if the transaction never ran.

11. Having been attempted, a failed transaction is still recorded, and the

Ether spent on GAS for its execution is deducted from the originating

account and otherwise has no other effects on the contract or account

state.

Smart contract advantages

The advantages of a smart contract include:

1. No changes to data can be made by a third party, i.e., it is immutable.

2. A network is formed around the apps, i.e., it is corruption-free and

tamper-proof.

3 . It is secured using cryptography and has no central point of failure; the

applications are well protected against hacking attacks and fraudulent

activities, i.e., it is secure.

4. Apps can never be switched off, and they never go down, i.e., Z ero

downtime.

To sum up, automatically executable programs are smart contracts; it is

software script describing the relationship of their users. As a matter of fact,

it is similar to legal contracts, only with some differences. The smart

contract algorithm is stored by the blockchain, and the action starts under

certain “if-then” conditions. All actions are controlled by a pre-written

program, and the absence of intermediaries is the main advantage of smart

contracts.