Hi guys, I was just looking at Etherscan.io and realised that a lot of blocks have 0 TX's within them and a lot have small numbers like 2tx's or 5tx's. I had previously assumed a block would be jam packed with hundreds of transactions. Looks like this is not the case. Would be grateful if anyone could provide a simple description of the contents of a block. Is the rest smart contract calculations? Is there always meaningful data in a block? cheers.