By Arvind Narayanan & Andrew Miller
Virtually unknown outside the Bitcoin community, a debate is raging about whether or not to increase the maximum size of Bitcoin blocks. Blocks are created in Bitcoin roughly once every ten minutes and are currently limited to a size of 1 megabyte, putting a limit on the rate at which the network can handle transactions. At first sight this might seem like a technical decision for the developers to make and indeed it’s largely being treated that way. In reality, it has far-reaching consequences for the Bitcoin ecosystem as it is the first truly contentious decision the Bitcoin community has faced. In fact, the manner in which the community reaches — or fails to reach — consensus on this issue may set a crucial precedent for Bitcoin’s long-term ability to survive, adapt, grow, and govern itself. 
If the Bitcoin protocol is decentralized and no one controls it, then how can it be changed at all?
You may know that Bitcoin is a decentralized system and that no single company, government, or entity controls it. In that sense it’s a lot like the Internet. But unlike the Internet, which is an ad-hoc collection of networks and protocols, and thus can be gradually upgraded piecemeal, all Bitcoin nodes are basically part of one giant distributed computation which means that upgrades need to be much more tightly — dare we say centrally — coordinated. The default Bitcoin software, Bitcoin Core, is that point of coordination. The five Core developers have a huge amount of power in determining how the network operates and in making upgrades to it.