Blockchain-based systems and networks record information (transactions) as blocks. Blocks are groups of transactions that are confirmed and then added to blockchains. When blocks are added to blockchains, all nodes on the network receive a similar copy of the block information.
Block time meaning also refers to the speed of transactions, recorded in transactions per second (TPS). Blocks are added in chronological order, with the newest blocks added on top of the older ones. Block time varies from one blockchain to another; the Ethereum block time is lower than the Bitcoin block time, meaning the Ethereum blockchain is faster than Bitcoin.
Block time may also refer to the average time mining nodes take to solve the transaction hash on a network. This time depends on the hashing difficulty at the time and also on the network activity.
Two major targets of blockchain scalability are increasing the network speed and reducing the block time. For example, the block time Bitcoin is currently 10 minutes. Any network upgrade to improve the speed and lower the block time will target reducing the network difficulty, possibly increasing the block size.
There are several proposals for improving block time; each one targets the factors affecting transaction speed (network difficulty, block size, network congestion, and stability). Proof-of-stake (PoS) consensus blockchains typically have a lower block time than proof-of-work (PoW) consensus blockchains.
This is because the latter involves many miners competing to verify transitions and add blocks, whereas the former involves a simpler and easier transaction verification process. Blockchain scalability improves every feature of blockchain transactions and makes building and deploying projects, protocols, and smart contacts easier when the block time is lower.