- Green area: Total (not active) full nodes downloaded by protocol;
- Blue line: Annual % change in total full node count.
Ethereum's node count is not charted in this research. For detailed stats on the Ethereum network's active and total nodes, see here.
Note that the Dash masternode count is in fact a subset of the total node count (nodes can still be run for free with Dash, as with Bitcoin):
Node count explained
Nodes are an integral part of why we call blockchains distributed and decentralized. Nodes are responsible for essentially "hosting" the network, just as you need a server hosting service if you have a website. Anyone in the world can "run" a node. All you need to do is download the latest, active version of the open-source software for that respective blockchain. Nodes communicate with one another and with "miners." Nodes contain, verify and broadcast the entire blockchain—including all of its transactions, from the very first day, from the very first block (the genesis block), until today.
The proper "role" of nodes in securing a global blockchain network is often debated. How many nodes is enough? In Bitcoin, the blockchain size is quite large, over 100 gigabytes, allowing for less incentive to host a node, even if you are a professional (let alone an enthusiast). Indeed, many miners and exchanges have marketed their efforts to increase decentralization and security by "donating" nodes to the network, additionally running 10, 50, or 100 nodes on dedicated servers, in order to keep the transaction information propagating across a truly global web of computers.
The verdict is still out as to what metric best describes how "decentralized" and "distributed" nodes actually make a blockchain's network. Included in a response to Bitcoin’s infamous scaling debate, creator Satoshi Nakamoto mentioned the role of nodes in the context of hindsight which he did not have when launching the Bitcoin project:
Please note, Bitcoin does not need appeal from authority to function, even from its creator. Nor does any other blockchain. Yet it could be noted that Nakamoto's statement does seem to describe Dash's "masternode" system. Dash masternodes essentially add a "staking" level to the Dash blockchain. Dash relies on miners to secure its network, just as in Bitcoin; but, unlike Bitcoin, the Dash block reward is split up among:
- Decentralized treasury
- Masternode owners
In order to host a masternode, any individual can "deposit" 1,000 DASH in a locked escrow (of sorts), and in return for doing so they're entitled to a portion of each block reward as interest, for as long as they continue to run the masternode. This is an interesting incentive. Masternode owners have other functions as well, such as verifying instant transactions, verifying private transactions, the ability to vote on the general direction of the network, and the ability to vote on how funds in the decentralized treasury are spent.
Note that the charts above are not graphing active nodes. Graphed above are those computers which have downloaded the latest client software of each respective blockchain. Active nodes—those running at any given time—are a subset of the pictures painted above. A good reference for active nodes can be found at BitInfoCharts.