Explaining blockchain to newcomers

[David Latapie]

I'm willing to make it as easy as possible (simple words, short sentences...) to understand some aspects of cryptocurrencies to newcomers. Targets are your neighbour, you mum, your MP....

The following text is by no means complete - it doesn't even start with "what is a cryptocurrency". I'm not looking for something complete, just for something internally consistent. Completeness will come later.
Please tell me if 1) this is correct 2) this seems simple enough. A good test would be to ask IRL, non-crypto friends about it. I appreciate your help.
(single point of failure: please provide a layman way to explain)

What is double-spending?
Double-spending is a complicated word for a simple thing:
Computer : easy to copy
Money: you don't want it to be copied

How to solve double-spending?
Solution #1 (up to 2009): central authority + trust it will behave honestly (adding layers of security only reduces the risk, without annihilating it - "who watches the watchmen?").
Solution #2 (from 2009 on): unforgeable logs, called "blockchain" (you can still copy the data, but that won't make a difference - you just have backup). "Trust" is placed on maths.

Why bother with blockchain?
Because you want something resilient to attacks on the central authority. This matter mainly concerned alternative currencies. Like the regulated currencies (fiat: euro, dollar...), they needed a central authority since we did not know any other way to prevent double-spending. And a central authority means a vulnerable, single point of failure.
Satoshi Nakamoto, January 2009

I think there were a lot more people interested in the 90's, but after more than a decade of failed Trusted Third Party based systems (Digicash, etc), they see it as a lost cause. I hope they can make the distinction that this is the first time I know of that we're trying a non-trust-based system.

What's this crypto 2.0 thing?
We came to realise that there is more than money were we need unforgeable logs. So what was first a monetary thing outgrew its original scope. Hence crypto 2.0, willing to extend the solution to other aspect of society (contracts, evidences of anteriority...)

[pereira4]

I've tried to explain the concept of the blockchain to my parents and they just dont get it, because they dont see why there has to be a public ledger for every transaction.

[David Latapie]

I've tried to explain the concept of the blockchain to my parents and they just dont get it, because they dont see why there has to be a public ledger for every transaction.

Interesting. Do they understand why there is a ledger at all? If not, then you should give them a lesson of Accountancy 101. If the issue is the "public" part, well, I don't know yet what to do, but probably it is not that difficult either

On another note, I just finished reading The Stateless Currency and the State: An Examination of the Feasibility of a State Attack on Bitcoin. It is damn interesting as a whole (I mentionned it on my cryptofiat thread) and the excerpts below are particularly interesting for general education:

When one spends cash, it is simply spent; that is, when a specific physical bill is used to purchase one good, it cannot also be used in a separate purchase at the same time. Electronic currency, however, is not tied to a specific physical object. Rather, it is stored in the form of data, which can be easily replicated. As such, double-spending electronic data essentially requires nothing more than making a copy of that data and sending it to two separate vendors. To be sure, one could “double-spend” cash by creating counterfeit copies, but the double-spending problem with electronic currency is all the more salient because copying data requires almost no additional effort. Furthermore, copied data, unlike counterfeit bills, is literally indistinguishable from the “original.
[...]
As Jerry Brito points out, the traditional solution to this problem of doublespending with electronic currencies was to trust a central third party, e.g. a bank or credit card company, to maintain the authoritative record of all legitimate transactions. Bitcoin, however, eliminated the need for such a third party by distributing the burden of maintaining that authoritative record of transactions across a decentralized network of “miners
[...]
Therefore, where centralized schemes require trust in the central authority, Bitcoin requires trust in the idea that the majority of mining power will be aimed at adding legitimate blocks to the block chain.
[...]
The role of trust, therefore, is not done away with in Bitcoin but merely repackaged.
[...]
There is no predetermined central authority in Bitcoin, but the possibility of one emerging is ever present.

[jbrnt]

Good effort OP!

You still haven't explain what is the blockchain. You could explain why there is a blockchain, what trust issues did it solve, and how are they linked together.

[David Latapie]

You still haven't explain what is the blockchain. You could explain why there is a blockchain, what trust issues did it solve, and how are they linked together.

"How to solve double-spending?" deals with your first sentence. "Why bother with blockchain?" deals with your second sentence

[pleaseexplain]

blockchain  - if they are old enough they will remember actually getting paper deeds to their house. that tracks who has owned it before and it lists them as the current (last) owner. The document is produced and certified by a central authority. it is very "blockchain-like". They can then see that if future house buyers are happy enough to buy their house when other homeowners confirm they are the real owners that is all that matters. ie a sale will take place with out a central authority. (in New Zealand you no longer get actual deeds so its an easy idea to explain)


as regards double spend - they will all have experienced a range of issues with their credit card. Invariably the credit card company has sorted it out for them. ie they know it could not have been sorted out any other way. If then there is no equivalent to a credit card company with bitcoin they see it as logical (and necessary) to stop any chance of confusion occurring as their is no person to fix it.

[hennessyhemp]

It's a record of previous transactions dated back to the creation of the first bitcoins generated in 2009.  The bitcoins are like blocks (in fact to generate them you have to "solve" a block), the ledger is like a chain holding the system together and recording every transaction so people can't spend the same money twice (double spend).

If the system were not public, than double spending and central authorities would reign supreme, and trust would be issued to a Paypal like entity to oversee it, unless more clever methods are devised (checkout Darkcoin and some other similar projects).

Just my two bits anyway.

[Q7]

The problem we are facing right now is that the society nowadays are generally I would say quite content and happy with the way things are going right now. Anything new and somehow a jargon for their understanding has always being given the cold treatment. So it's not the complexity of bitcoin that becomes the problem. It's the people

[izanagi narukami]

Is that true, blockchain can be hack even I never click any suspicious site ?
and
I have no virus on my PC.

How to protect blockchain from being hack ?

[mistercoin]

Oh man I hate it when people who are technically-declined ask me to explain Bitcoin to them. I can never seem to find the words to explain it to these types.

[finnile]

Oh man I hate it when people who are technically-declined ask me to explain Bitcoin to them. I can never seem to find the words to explain it to these types.

Best to just tell them what it is, rather than the details of how it works.

[neurotypical]

I've tried to explain the concept of the blockchain to my parents and they just dont get it, because they dont see why there has to be a public ledger for every transaction.

Interesting. Do they understand why there is a ledger at all? If not, then you should give them a lesson of Accountancy 101. If the issue is the "public" part, well, I don't know yet what to do, but probably it is not that difficult either

On another note, I just finished reading The Stateless Currency and the State: An Examination of the Feasibility of a State Attack on Bitcoin. It is damn interesting as a whole (I mentionned it on my cryptofiat thread) and the excerpts below are particularly interesting for general education:

When one spends cash, it is simply spent; that is, when a specific physical bill is used to purchase one good, it cannot also be used in a separate purchase at the same time. Electronic currency, however, is not tied to a specific physical object. Rather, it is stored in the form of data, which can be easily replicated. As such, double-spending electronic data essentially requires nothing more than making a copy of that data and sending it to two separate vendors. To be sure, one could “double-spend” cash by creating counterfeit copies, but the double-spending problem with electronic currency is all the more salient because copying data requires almost no additional effort. Furthermore, copied data, unlike counterfeit bills, is literally indistinguishable from the “original.
[...]
As Jerry Brito points out, the traditional solution to this problem of doublespending with electronic currencies was to trust a central third party, e.g. a bank or credit card company, to maintain the authoritative record of all legitimate transactions. Bitcoin, however, eliminated the need for such a third party by distributing the burden of maintaining that authoritative record of transactions across a decentralized network of “miners
[...]
Therefore, where centralized schemes require trust in the central authority, Bitcoin requires trust in the idea that the majority of mining power will be aimed at adding legitimate blocks to the block chain.
[...]
The role of trust, therefore, is not done away with in Bitcoin but merely repackaged.
[...]
There is no predetermined central authority in Bitcoin, but the possibility of one emerging is ever present.

If you dont have a public ledger there would be a risk of double spending, but most people say "if the system is so safe and the algorithm cant be cracked then why do you even need it?"

[TheDreadPirateDickstein]

I'm willing to make it as easy as possible (simple words, short sentences...) to understand some aspects of cryptocurrencies to newcomers. Targets are your neighbour, you mum, your MP....

The following text is by no means complete - it doesn't even start with "what is a cryptocurrency". I'm not looking for something complete, just for something internally consistent. Completeness will come later.
Please tell me if 1) this is correct 2) this seems simple enough. A good test would be to ask IRL, non-crypto friends about it. I appreciate your help.
(single point of failure: please provide a layman way to explain)

What is double-spending?
Double-spending is a complicated word for a simple thing:
Computer : easy to copy
Money: you don't want it to be copied

How to solve double-spending?
Solution #1 (up to 2009): central authority + trust it will behave honestly (adding layers of security only reduces the risk, without annihilating it - "who watches the watchmen?").
Solution #2 (from 2009 on): unforgeable logs, called "blockchain" (you can still copy the data, but that won't make a difference - you just have backup). "Trust" is placed on maths.

Why bother with blockchain?
Because you want something resilient to attacks on the central authority. This matter mainly concerned alternative currencies. Like the regulated currencies (fiat: euro, dollar...), they needed a central authority since we did not know any other way to prevent double-spending. And a central authority means a vulnerable, single point of failure.
Satoshi Nakamoto, January 2009

I think there were a lot more people interested in the 90's, but after more than a decade of failed Trusted Third Party based systems (Digicash, etc), they see it as a lost cause. I hope they can make the distinction that this is the first time I know of that we're trying a non-trust-based system.

What's this crypto 2.0 thing?
We came to realise that there is more than money were we need unforgeable logs. So what was first a monetary thing outgrew its original scope. Hence crypto 2.0, willing to extend the solution to other aspect of society (contracts, evidences of anteriority...)

Just go up to someone and tell them they can buy drugs with it, or if the like gold, tell them it's like digital gold....only pitch you need.....stop calling it TECHNOLOGY. It's killing it.