Could you explain why you think that users don't need to run network nodes?
I don't agree, but I would like to understand your point of view.
The design of Bitcoin is such that users can just be users.
For example, if I transfer a coin to you, you can immediately verify my signature. You do not need to trust me or trust anyone else -- the transaction itself contains cryptographic proof that I transferred ownership of my coin to you. You can even follow the chain of signatures backwards and confirm that the person who I received the coin from also signed the transfer, and so on and so forth, as far back as you want to go. You do not need a network node to do this!
The only risk
to you is that I may have also signed that same bitcoin over to someone else. This is the double-spend problem that had not been solved until Satoshi. Satoshi's revolutionary solution was to use proof-of-work to time stamp transactions into a chain such that -- if his proof-of-work conjecture held -- that the same coin could not be spent twice.
As a user then, the only additional piece of information you need, is whether the transaction I gave to you was accepted into the blockchain. A network node can provide you this proof (that you can trustlessly verify for yourself!) with a few kilobytes of information.
Here is a talk I gave (only about 10 min long) that explains how SPV works in more detail (sorry about the crappy audio!)
https://youtu.be/m7cvPvtGIUI?t=459Thanks, I appreciate your response, but you talk to me about just one function of the node, which is to keep a record of the transaction history. Is not it also the function of the node to enforce the set of rules that maintain consensus in the network?
This is not a node
https://blockchain.info/access to all of bitcoins transactions
nodes confirm transactions besides other things, this is the blockchain
nodes are usually pc wallets, miners, pools, exchanges etc
side chains, wallet apps, online wallets are not full nodes and rely on the above infrastructure
hope i got that right
bitcoin is a currency of the bitcoin blockchain, the blockchain is the key
to use bitcoin effectively
1) Imagine if someone took a record of all your transactions from currency to contracts and anything else that can be electronic
2) Now you go and build your automation/software around that decentralized transparent ledger
3) The trust in your accounts/organisatioon/industry/currency is now exponentially better than anybody else
You are only limited by your imagination and do not need to be a node