The block #540107 was mined in the main network of bitcoins, which is the largest in the history of cryptocurrency. The size of this block – 2.259 MB. This was reported by Conan O’Bitcoin in his Twitter account.
— Conan O'Bitcoin (@ConanOBitcoin) September 9, 2018
This was made possible by the implementation of the Segregated Witness (SegWit) protocol and the introduction of batching of transactions.
Segregated Witness is a protocol update that is designed to solve the problem of the plasticity of blockchains transactions and increase bandwidth. A similar update was made for other cryptocurrencies. This list includes Litecoin, DigiByte, Groestlcoin and Vertcoin.
SegWit is a “soft fork” and allows the network to function in the former mode. However, the structure of data storage in the block and the mechanism for verifying transactions for full-fledged network nodes are changing. Now signatures and scripts are allocated in a separate structure, called a “segregated witness”. This allows the main block to accommodate more transactions, and also eliminates the variability of the identifier of the same transaction.
The extended block is theoretically limited to 4 megabytes, but in fact the maximum block size is just under 2 MB.