Mina is a layer-1 protocol with a succinct blockchain. The current blockchains like Bitcoin and Ethereum store hundreds of gigabytes of data, and their blockchains will only increase in size over time. With Mina, the blockchain always stays the same size - about 22kb (the size of a few tweets), regardless of the growth in usage. This enables users to quickly sync and verify the network, which helps to increase network decentralization and reduce the vulnerability to a 51% attack on the network.