please suggest me best source to learn blockchain technology

Answer 1

The basics of blockchain can be found on youtube.
First of all, learning how SHA-2 works, how bitcoin blockchain works, the genesis block might be a deep reading for you if you're new into, but learning C++, solidity(for eth environment, smart contracts, etc), which it's being compared to js.
recommendation
a MUST READ: "Mastering Bitcoin: Programming the Open Blockchain" by Andreas Antonopoulos.

Answer 2

Very good book about Blockchain - Decentralized Applications, Siraj Raval