Sharding is a way to split up the blockchain into different parts that can be processed in parallel. This helps to scale the blockchain so that it can handle more transactions and data
In an effort to improve the scalability of blockchains, sharding has been floated as a solution. Under the current dynamics, each node stores all the information present in the blockchain (i.e. account balances, storage data, transaction logs etc).
Because blockchains can’t process more transactions than a single node can, the scale of a blockchain is limited by the amount they can do. Sharding is a form of portioning that separates larger databases into smaller ones.
Doing this can distribute the workload and improve the speed of transactions. In essence, sharding separates nodes into smaller sections but keeps them linked in a single structure. That, in theory, can make blockchains larger and faster but remain secure and decentralized.