Thanks a lots. You all very kind to teach me. I appreciate your suggestions.
Is it true that Bitcoin and Blockchain do not have a central server ? If it is true then it is good. But if Satoshi Nakamoto secretly running the Central Server where all the Bitcoin data's are stored then how Bitcoin is decentralised ?
I think you answered your own question. Bitcoin is decentralized, that means there is no central server.
It wouldn't be called decentralized if it wasn't. And, believe me, there are smart people and programmers who know how to verify such things since the entire code is open source and anyone can read it.