Example of a Block:
When a block is discovered, the discoverer may award themselves a certain number of bitcoins, which is agreed-upon by everyone in the network. Currently this bounty is 25 bitcoins; this value will halve every 210,000 blocks. See Controlled Currency Supply.
Additionally, the miner is awarded the fees paid by users sending transactions. The fee is an incentive for the miner to include the transaction in their block. In the future, as the number of new bitcoins miners are allowed to create in each block dwindles, the fees will make up a much more important percentage of mining income.
Where is the blockchain stored?
Blockchains are stored in a lot of people’s computers. These people are called nodes. They can be simple users or miners.So each node has a copy of all transactions ever made. So what happens when a new transaction is written to the blockchain (added to the spreadsheet)? Well, all computers storing the blockchain have to update it!