A node describes one computer, among many computers, running the G1 currency blockchain.

The nodes are computers that run the Duniter software, which is managing the Ğ1 blockchain. In 2022, there are around 200 nodes running the Ğ1 blockchain. [note Hugo] 200 nodes have been computing blocks, I'm not sure of this number. Where is the source? [end note Hugo]

These computers are set up by Ğ1 users or Ğ1 co-creators if they choose to do so (it's optional for anyone in the G1 network). They tend to be small devices, most often personal laptops or PCs or even nano computers, like the popular credit card sized Raspberry Pi.

Each Duniter Node verifies that each block content respects all the Ğ1 rules: web of trust rules (if G1 co-creator accounts's certifications are up to date, if they respect the distance rule, if the account is not revoked), monetary rules (calculation and creation of UD on G1 co-creators' accounts, calculation of transactions between accounts, cancellation of transactions leading to negative amounts on accounts) and blockchain rules (see Duniter blockchain). The block calculation is designed to last 5 minutes on average. 

Each node holds a private key connected to a Ğ1 wallet.

They are 2 different kinds of node:

• "Forger" nodes: These nodes are connected to a Ğ1 currency co-creator's private key (so only Ğ1 co-creator's can run a Forger node). These nodes can write a completed block (of transactions) into the Blockchain;
• "Mirror" nodes: These nodes are not connected to a Ğ1 currency co-creator's private key (so one does not need to be a Ğ1 co-creator, and have the subsequent private key, to run a Mirror node). They do not have any power or influence over the Duniter blockchain, as these nodes contain copies of the blockchain and are used only to communicate with Ğ1 Clients.

Currently, the Cesium Client allows you to choose your own Duniter node from a list of Mirror nodes. It's best to choose one that is different from the people in your G1 local community so that the work load can be spread out amongst the available nodes.  

[note Hugo] we use "smith" more than "forger" [end note Hugo]