Bitcoin is gearing up for what could be the biggest (and least understood) change to its software to date.

Often called simply a “digital currency,” bitcoin is best viewed as a protocol (a set of code) that delivers data (in this case bitcoins) in defined quantities (called blocks) that are then stored in a sequence (called a blockchain) on a distributed set of global computers. Bitcoin is decentralized – in that many people help make the network function, and in choosing to run its software, users all agree to abide by the same rules to keep it operational.

It’s these qualities that make the proposed change particularly divisive.

Called Segwit2x, the plan calls for a very specific fork (or a change to bitcoin’s rules), one that would make certain rules valid that weren’t valid before. Specifically, Segwit2x would change the size of the blocks passed regularly around the network and stored in the blockchain from 1 MB to 2 MB.

Some users think this is a good idea, others don’t.

But to begin, it’s important to note how this fork differs from others. Coming on the heels of the bitcoin cash and bitcoin gold forks, bitcoin users might be accustomed to certain outcomes – ones that might not be guaranteed in the case of Segwit2x.

With bitcoin cash and bitcoin gold, for example, bitcoin users could have paid little to no attention and it wouldn’t have impacted their transactions. If you held bitcoin on certain exchanges (or your own wallet), you received new cryptocurrency.

This smooth outcome, however, isn’t guaranteed with Segwit2x. Complicating matters is that in many ways, Segwit2x sounds (and is) similar to other bitcoin forks.

Read more: CoinDesk