Blockchain Basics & Transactions

Bitcoin Transaction Format

Generation of a freshly minited bitcoin
The only input is the coinbase block reward
Reward halves every 210,000 blocks (originally 50 bitcoins per block)
May include 100 bytes of arbitray data
The Genesis Bock included Headline from Financial Times: “The Times 03/Jan/2009 Chancellor on brink of second bailout for banks”

genesis-block

translated into

genesis-translated

A UTXO is like the change we receive in a cash transaction which can be used for future transaction. It is a transaction output that can be used as input in a new transaction.
Like a note or a coin, a UTXO can not be split. However, new UTXOs can be created. For example, assuming i have a UTXO of 0.8 bitcoin and another UTXO of 0.6 bitcoin. If I wish to send 1 bitcon, the two UTXOs will be used as inputs for the transaction and be destroyed, or spent. Two new outputs will be created, one worth 1 bitcoin sent to the recipient and another worth 0.39 bitcoin (since there is transaction fee) sent back to me.
UTXO addresses the double spend problem.
A UTXO set contains all the currently unspent bitcoins and is stored using a LevelDB database in Bitcoin Core called “chainstate”
The sume of all UTXOs equal to the total bitcoin in circulation.