Network sharding allows parallel transactions processing. Whenever a transaction reaches the network it gets assigned to a specific shard and is independently processed in order to yield high throughput to the network.
Zilliqa network reaches over 2,500 transactions per second.
Practical Byzantine Fault Tolerance (PBFT)
In PBFT, each blockchain shard relies on a group of nodes to confirm a subsection of all the transactions, and once each shard has reached a consensus, the second group of nodes confirms the shards' collective results and adds a new block to the blockchain. This means that if PBFT is used to reach consensus on the next block, then the proposed block is final and the agreement is exact.