I am a newbie in Blockchain technology and found a word "smart contracts". I have searched about it and the only answer I got is....it is a program, which executes some statement, if certain conditions are met.
But I want to know, how this is is useful in Blockchain technology.
When this program is executed??
Does every node have their unique set of smart contracts??
Data Mining is the process of validating the transaction, then why smart contracts are used ?
Please give me an example where smart contracts are actually executed in Blockchain.