Blockchain - Merkle Tree
Since every transaction in a block is hashed in a Merkle Tree, the issue of disk space in a node is easily overcome.
Block headers now contain a hash of the previous block, a Nonce, and a Merkle Tree containing the Root Hash of all transactions within the current block. In order to save disk space, the Root Hash includes the hashes of all transactions in the block, which can then be pruned to save space. The blockchain now looks like the image below.
As a result, a normal client who just wants to receive payments from others can save a lot of disk space by using this strategy. Miners, however, must keep the entire blockchain in order to verify the payment. Next, we explain how the receiver verifies the payment without being able to trace the coin back to its source.