Proof of Work: Blockchain

How is the data secured in blockchain
The answer is: Proof of Work
What is Proof of Work and how it works?
-> Proof of Work is nothing but a mathematical puzzle, whose solution is a hash value which is very long and its hard to compute its hash key
-> Atleast 51% of the miners should agree with a hash value to get it registered on blockchain
-> It requires a lot of computational resources to generate a valid hash value