The Blocks and the Chain

Understand what a blockchain ledger is and how blocks are joined together to form a chain.

In this lesson, we’ll learn the logical components of a blockchain and how they work together in a complex but fascinating and precise way.

A blockchain deals with two types of data:

  • Permanent data (that can never be changed).

  • Ephemeral data (that can be changed).

This is the principal distinction between the two parts that consitute a blockchain ledger:

  • The world state (ephemeral).

  • The blockchain (permanent).

Let’s look at these two components in detail to understand how they are so closely related.

The world state

A status is a mapping between a label and some data. We refer to the label as the key and the associated data as the value. In a distributed ledger, a key identifies an account and the value is a set of information tied to that account. We’ll explore what an account is later in a dedicated lesson.

A world state is the set of all blockchain statuses at a certain moment. The following image shows a simplified visual representation, where the value tied to accounts is basically a balance

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