Blockchain is a Distributed database that maintains the details of each transaction in a series of blocks and those transactions will be added to the ledger in chronological order. The Stored transaction details in a block called genesis block.

Normally a block consists of

previous hash(I.e hash of the previous block ),
data(I.e sender address,receiver address,transaction amount);
hash(I.e like a unique digital fingerprint)
nonce(I.e Random value)