Overview

Block is the basic element in a blockchain system, as we known blockchain system is just a ledger, which means a bookkeeping1 that recording of financial transactions. In the blockchain system, those transactions are stored in the blocks. In each block, the data stored in may look like:

TXN FROM TO VALUE
#0 God Cale 100
#1 Cale Alice 10
#2 Alice Bob 1
#3 Bob Mike 0.5

Then what’s a blockchain? Just simply chain the blocks together, usually add a field to point to its parent:

  • Blocks #0

    Parent: None

    Data:

    TXN FROM TO VALUE
    #0 God Cale 100

  • Blocks #1

    Parent: #0

    Data:

    TXN FROM TO VALUE
    #0 Cale Alice 10
    #1 Cale Mike 1

  • Blocks #2 Parent: #1

    Data:

    TXN FROM TO VALUE
    #0 Alice Bob 1
    #1 Mike David 0.5

  • Blocks #3

    Parent: #2

    Data:

    TXN FROM TO VALUE
    #0 Bob David 0.5

As above shows, we can figure out each person’s balance:

ACCOUNT BALANCE WHY?
Cale 89 +100 from god, -10 to Alice, -1 to Mike
Alice 9 +10 from Cale, -1 to Bob
Bob 0 +1 from Alice, -0.5 to Mike, -0.5 to David
Mike 0 +0.5 from Bob, -0.5 to David
David 1 +0.5 from Bob, +0.5 from Mike

  1. https://en.wikipedia.org/wiki/Bookkeeping ↩︎