How Is Block Assembled? I think I understand mining well enough, but what I don't get is how the blocks of transactions are assembled. According to this post - What exactly is Mining? - the miners assemble the blocks and then solve for the difficulty. 

So, once a block is solved and the miners need to create a new block, how do the miners decide how many transactions to put in the block? Could the miner just assemble a block with a single transaction? Could certain blocks contain more or less transactions than another? Thanks!
Technically a block with just one transaction in it would be valid. However miners have an incentive to add more transactions to the block they are currently mining because they receive the transaction fees attached to those transactions.