Proof of work
In short
Proof of work is Bitcoin's security scheme: writing blocks requires measurable computational work, making fraud more expensive than honesty.
The "work" is trying numbers billions of times until a valid block hash appears. Critics target the energy use; supporters see exactly that as the incorruptibility.
What happens in a 51% attack?
Whoever controls most computing power could delay or double-spend transactions — at Bitcoin's scale that is practically unaffordable.
Related terms
Information, not investment advice. More of this? The newsletter.