"How important is it to be running a full node as a user of bitcoin?"
It is important to you, as a user of bitcoin.
If you want to know if a transaction has been confirmed, [especially] if you have received a payment,
there are two ways to find out.
One way is to [access] a block explorer [by] typing in "blockchain.info," "blocktrail.com," "blockcypher.com,"
or one of these other blockchain explorers.
That tells you they think, [or want you to think], that the transaction has been confirmed.
You only know that if no one has hacked them,
there isn't a bug in their [node is] producing misleading information,
they haven't decided to directly mislead you,
or your own computer and browser aren't compromised [to] display false information.
[Using a block explorer], you don't really know if the transaction has been confirmed .
If you then use that information to make decisions, [especially] expensive decisions...
[such as] letting someone [who supposedly just purchased your car] drive off with it,
because a block explorer said they have paid you and there has been three confirmations,
you are delegating the responsibility [for validation].
The trust model is broken. You should not be delegating that responsibility.
You should use your own node that you properly [and independently] configured [to] stay within consensus,
properly upgraded to the software version and types of capabilities that you feel comfortable with.
You should ask that node [whether you have received a payment]; it will give you an [independent] answer...
based on its own evaluation of the consensus rules.
Can most users [currently] do that? No.
[But] certainly [people] who are running companies need to [run their own node];
people who are [developing and servicing] wallets with a lot of money need to do that.
Most users won't, most users are using lightweight wallets, but they do so at a cost to themselves.
The cost is certainty [about their transactions].
That doesn't mean it is not also an issue for the rest of the network [if you are not running a node].
It is not only good to run a node for your own reasons, but more people running nodes...
[to] check if a transaction has been confirmed and [basing] economic decisions on that, is meaningful.
If you are simply running a node on Amazon Web Services, where it costs you $15 to [set it up],
that does nothing because it is on infrastructure you don't control.
It doesn't really do anything. Maybe paying for some of the bandwidth will help [new] nodes to bootstrap,
but your control over that is very limited.
It is important, if you have the ability, to run a node on your own [internet] connection, your own hardware...
in the security of your own home or office.
If you can run it with a satellite feed, even better!
If you can reconcile what is coming from the satellite with the internet, even better!
You [would] increase the resilience and robustness of [yourself and the Bitcoin network]. Do it for principle.
But again, not many can do that.
Max asks, "Is it more important to have decentralization among miners, nodes, or both? Why?"
It is important to have decentralization in every aspect of Bitcoin. Centralization is a point of weakness,
a point of potential failure, corruption, and take-over.
When we [talk about] decentralization of miners, we [need] to think of it in three very distinct ways.
Maybe even four different ways.
First, the manufacturing of mining hardware, specifically the high-end, cutting edge...
16 to 12 nanometer silicon fabrication of ASICs.
Centralization in [manufacturing] can drive centralization in the [other areas].
Next, the ownership of mining hardware itself.
The mining "farmers," or miners who own the mining farms, if you want to call them that.
What we mean when we say "miners" are the people who own mining equipment.
If only a few organizations own mining equipment and control how it is being used, that is a problem.
Then there is decentralization of mining geography.
Even if the mining equipment is owned by lots of [different] people [or organisations],
if it is housed in only a few locations, in terms of the same warehouse or same geographic vicinity,
that is a problem.
Right now, a very large percentage of the mining equipment, while controlled by many miners,
is located primarily in two provinces of China.
Geographically, that is not good.
Finally, mining pools, where multiple miners spread out their gains and smooth out the probability distribution...
of finding blocks and reward.
We need decentralization in that.
Among miners, we need decentralization in manufacturing, ownership, geography, and pools.
We also need decentralization in nodes and the types of nodes [people run].
Nodes used by individuals to run wallets (as I do), nodes used by intermediaries for merchant services,
nodes used by merchants to run e-commerce sites, nodes used by companies to run wallet infrastructure,
and nodes used by exchanges.
All of those need to be decentralized; we need as many of those types to run, in as many geographies,
through as many [different types of connections]: internet, dial-up, leased line, microwave, satelitte...
Whatever else we need to use. Frequency-hopping spread spectrum (FHSS).
Decentralization everywhere is the key here; decentralization in as many places [as possible].
Of course, these things will ebb and flow over time. We will see some areas become more centralized,
then become more decentralized again, then perhaps re-centralize.
[These areas will not] all move in the same direction at the same time, which is a good thing.
Changes in technology, operational models, profitability, supply chains, will affect decentralization [tendencies].
For example, in the manufacture of ASICs, the biggest change that has happened [recently] is,
we finally caught up to Moore's law and [now] we are right at the front end of that,
which slows down the incremental improvements in mining capability and performance significantly,
by orders of magnitude in fact.
That changes the dynamics of the supply chain.
Now you can actually ship [those chips] and it will not be obsolete by the time...
it arrives [at its destination] a thousand kilometers away.
You can put it on a container ship for two months and it [will] still be...
useful hardware after [those] two [shipping] months.
This changes the decentralization of ownership and geographic [distribution] of mining equipment.
Sometimes we will have external shocks to the system, [such as] if a country starts cracking down [on mining].
When Venezuela bans mining or requires everybody to [apply for] a license... it's a trap! Don't get a license.
They will find you!
But when Venezuela [does it], that wouldn't have a big impact [on the whole network].
If China was to [ban mining or require licenses], that [could] dramatically change the economics.
It would make centralization of mining an [obvious] disadvantage.
It would actually lead to decentralization of mining, if that happened.
Lucas asks, "Is it possible to run a Lightning node for a few hours a day, like a full node?"
"Does shutting down a Lightning node disrupt Lightning [payments]?"
Yes, it is possible to run a Lightning node only part-time.
If you [want to] shut down your node and have outstanding channels that are open,
you [may use] a [watchtower] to monitor for channel closure [if you plan to be offline...
for longer than the timeout period], to make sure [the other participant in the channel] doesn't try to cheat...
by broadcasting a prior state.
One of the interesting innovations in the Lightning protocol, [which was developed] after the original paper,
was a great contribution by Thaddeus Dryja and Olaoluwa Osuntokun.
They implemented the ability to give a third-party a role to monitor for cheating in Lightning payment channels.
The only way you can cheat in [certain payment channel designs] is by re-transmitting a prior state...
which has been revoked, [in order to get] a more preferential balance on your side of the channel.
[For example, you could] pretend that you haven't actually spent some of that money in the channel.
There is a way to protect against that in Lightning.
If you try to do that, the other person being cheated has the opportunity to [use a revocation key]...
and transmit a countervailing transaction.
While you are waiting to get paid from your cheat transaction in three days [due to the timeout period],
they can immediately take the money.
Not just the money that you owe them, but the entire balance of the channel.
It is essentially a scorched-earth policy, where you are punished for trying to cheat by losing everything.
To do that, they [must] be online to catch you cheating without the timelock period,
when you are waiting for a confirmation.
If you are running a Lightning node part-time [and plan to be offline longer than the timeout period],
you will need to transmit those revocation states to a third-party who is running [a node] full-time.
If they see someone trying to cheat,
they will broadcast the punishment transaction to wipe the channel [in your favor], save you from being cheated,
and punish the transgressor.
The best part of that function is the innovation which [prevents] the third-party [from knowing]...
what channels you have open or how much money you have in those channels.
They will only know if they see a cheat. That is very cool. So you can run a Lightning node part-time.
It is [factored in to] the design, with the ability to [invite] a third-party to do the enforcement.
Anonymous asks, "How can a non-developers [become] involved with Lightning [right now]?"
If you have experience in user interface design, you can definitely [become] involved in Lightning.
If you don't, then you can download some of the existing Lightning wallets and start using them,
seeing where they work and don't work [for you].
Today, you [can only] use them on test-net, but that is okay.
Help with testing and give feedback to the developers.
Ultimately, a Lightning wallet [should] look like a [regular] Bitcoin wallet.
[Eventually], it should not be necessary for you to know where the payment you made...
was with or without SegWit, using Lightning or on the base blockchain [to a regular] bitcoin address.
It should not matter. You will basically scan a QR code, click 'pay,' and it tells you how long [until confirmation]
and [how much] it will cost [in terms of fees].
You, may notice some of your transactions are much faster and cheaper to execute.
Those are the Lightning transactions.
[Other] transactions are slower and a bit more expensive; those are SegWit transactions.
Some are very expensive and slow; those are [legacy] bitcoin transactions,
on a blockchain that is probably congested.
[If the interface design is good,] that is the only indication you should get.
Your wallet [does not need to] tell you how many channels you have open...
or who [you have] those channels [with], unless you go into some advanced setting.
All of that should be invisible to the end user. It should be usable like a [regular] Bitcoin wallet.
Not all of the Lightning wallets are like that.
Most of them are designed by (and for) [developers and] engineers at the moment.
They show a lot of background detail and are not very user friendly. Check out Eclair and Zap wallet.
Have a look at some of these wallets as they come out. Help with testing and give feedback [to developers].
I think that can be enormously helpful.
If you are a graphic design or user interface designer, even more so!
Paige asks, "The white paper emphasizes the need for honest nodes to control the majority of the CPU power."
"Is there a way for me, as a non-technical person, to help secure the Bitcoin network?"
No, there isn't. That aspect, which is the mining function, requires you to have significant processing capability.
It is managed entirely by specialised ASIC chips [now instead of] CPU, which [can be] difficult to source.
At the current level of competition,[mining] is a viciously competitive game that requires [significant] investment.
You can dip a toe into this pool, [but unless] you have $50 million to spare [to] hire some very technical people,
the average non-technical person cannot help secure the network through [mining].
But they can help secure the network by running a node at home, to validate [your own transactions]...
and to see if [you have] been paid, [or to help new nodes bootstrap] for example.
Maybe by connecting to a satellite dish.
Certainly by choosing very carefully which software to run, what types of wallets and exchanges to use.
Use [wallets and other software that] align with [your] own principles. That is very powerful.
You can [have a great effect] just through your choices as a consumer, and by running a node at home.
It is also a good learning experience.