Scaling Trilemma
Plain English
The challenge that blockchains face: you can typically only optimize for two of three things - security, decentralization, or scalability. Bitcoin prioritizes security and decentralization but is slow. Some networks prioritize speed but sacrifice decentralization.
Technical
Fundamental constraint proposing that blockchain systems can only optimize two of three properties simultaneously: security (resistance to attacks), decentralization (distributed control), and scalability (transaction throughput). Different networks make different trade-offs, while advanced solutions like sharding and layer 2 networks attempt to overcome these limitations through architectural innovations.