*https://medium.com/@VitalikButerin/the-meaning-of-decentralization-a0c92b76a274*

Vitalik Buterin, February 2017

“Decentralization” is one of the words that is used in the cryptoeconomics space the most frequently, and is often even viewed as a blockchain’s entire raison d’être, but it is also one of the words that is perhaps defined the most poorly. Thousands of hours of research, and billions of dollars of hashpower, have been spent for the sole purpose of attempting to achieve decentralization, and to protect and improve it, and when discussions get rivalrous it is extremely common for proponents of one protocol (or protocol extension) to claim that the opposing proposals are “centralized” as the ultimate knockdown argument.

But there is often a lot of confusion as to what this word actually means. Consider, for example, the following completely unhelpful, but unfortunately all too common, diagram:

Now, consider the two answers on Quora for “what is the difference between distributed and decentralized”. The first essentially parrots the above diagram, whereas the second makes the entirely different claim that “distributed means not all the processing of the transactions is done in the same place”, whereas “decentralized means that not one single entity has control over all the processing”. Meanwhile, the top answer on the Ethereum stack exchange gives a very similar diagram, but with the words “decentralized” and “distributed” switched places! Clearly, a clarification is in order.

Three types of Decentralization

When people talk about software decentralization, there are actually three separate axes of centralization/decentralization that they may be talking about. While in some cases it is difficult to see how you can have one without the other, in general they are quite independent of each other. The axes are as follows:

• Architectural (de)centralization — how many physical computers is a system made up of? How many of those computers can it tolerate breaking down at any single time?
• Political (de)centralization — how many individuals or organizations ultimately control the computers that the system is made up of?
• Logical (de)centralization— does the interface and data structures that the system presents and maintains look more like a single monolithic object, or an amorphous swarm? One simple heuristic is: if you cut the system in half, including both providers and users, will both halves continue to fully operate as independent units?

We can try to put these three dimensions into a chart: