Ethereum is sort of like Bitcoin, but includes a Turing-complete scripting language. Programs written in this language are called "smart contracts", and can do

Ethereum is sort of like Bitcoin, but includes a Turing-complete scripting language. Programs written in this language are called "smart contracts", and can do a much wider range of things than simply dealing with currency. One of the core principles of blockchain technology is immutability - that is, once a transaction becomes part of a blockchain, it stays there forever and can never be undone. In the case of Ethereum, this also includes smart contracts. An advantage of immutable contracts is that users can trust that it will always operate in exactly the way the code was written, and the developer who wrote the contract cannot change the rules, or alter the "terms of service" as so often happens in centralised systems. A disadvantage of immutable contracts is that if there is a bug in the code, it remains there permanently and can never be fixed. In this particular case, there was a bug that allowed someone to instruct the contract to "self destruct" (refuse to process any more transactions), thereby locking away a large amount of ETH. EIP stands for Ethereum Improvement Proposal. This particular proposal (which, as I understand, has not yet been accepted) would alter the Ethereum protocol to handle this specific contract address specially in such a way that reverses effects of the unintended self-destruction, allowing the lost funds to be recovered. This goes against the principle that the blockchain must be immutable, otherwise known as "code is law". Breaking immutability in such a manner is highly controversial; the debate is about whether the development team should make a one-off fix for this particular case because a lot of people lost a lot of money (or rather ETH), or whether they should leave things as-is to avoid destroying trust in Ethereum's promise of immutability. This has happened previously on one occasion; see https://en.wikipedia.org/wiki/The_DAO_(organization) https://en.wikipedia.org/wiki/The_DAO_(organization)