Zooko's triangle

Zooko's triangle is an idea about the difficulty of creating a part of technology called an "identity system". This is something that is used to identify us, like an online account, phone number, or email address. The idea behind Zooko's triangle is that the identity system needs to be secure, easy to remember, and decentralized.
Here's the tricky part: these three things are hard to have all at the same time. Security means that the identity system should be very hard for anyone else to access without permission. Easy to remember means that it shouldn't be too complicated and should be something that all users can remember. Decentralization means that no single company, person, or group should control the whole system.
Having all of these three things together is hard. That's why it's called the "Zooko's triangle"!