What Is SegWit?

Segregated Witness or SegWit is a protocol update developed by Bitcoin Core team. SegWit’s mission is to optimize the Bitcoin block structure which can be a solution to the long-standing issues of network scalability, block overflow, transaction speed, and commission size. In other words, SegWit improves Bitcoin blockchain’s efficiency without increasing the block size.

Softfork changes the rules of block validation in blockchain. But these changes do not affect the core code. Hardfork, on the other hand, is a more radical solution which can jeopardize the entire network in the case of a mistake. Thus, Bitcoin Unlimited is a hardfork of Bitcoin network.

First and foremost, Segregated Witness is a solution to Bitcoin’s scalability issues. SegWit changes how transaction signatures work which allows to optimize transaction block structure and fit more transactions into a block. SegWit, along with the Lightning Network, also facilitates faster transaction confirmation.

The main benefit of SegWit is creating more space for transactions in a block without increasing its actual size. In other words, SegWit improves blockchain’s throughput but also does not break the current consensus rules.

At the core of SegWit’s mechanics lies a new data structure which contains transaction signatures, basically allowing to remove them from the transaction itself. With the signature removed available space almost doubles, hence each block will be able to double the number of transactions while retaining its original size.

SegWit will also be of use to full node owners as it decreases the amount of data that has to be stored on the hard drives. In other words, SegWit allows to lower requirements for the launch of a full node and to decrease the time needed to sync with the network.

To activate any new solution in Bitcoin network support of 95% of miners is required. More precisely, once the activation threshold is reached 95% of all new blocks are mined by SegWit supporters for a period of 2016 blocks (approx. two weeks).

Bitcoin Core 0.13.1 which included SegWit was released on October 27, 2016.

SegWit’s popularity is currently on the rise. This is mostly due to the trust Bitcoin Core team has built within the community and multiple serious issues found in Bitcoin Unlimited’s code. Various services exist which allow to check which companies support Segregated Witness, Coin Dance being one of them.

In April 2017 SegWit protocol was implemented in the Litecoin network. There are other, less popular cryptocurrencies who signaled their support for Segregated Witness.