So, this is an interesting discussion with a 5+ year old . Challenge accepted. 

Me: So, do you know what money are?

5 year old (known from now on as 5): Yes, money are coins and notes that i use to buy toys and sweets. And sometimes clothes and shoes.

Me: Yes. But when you play on your tablet, do you use money also?

5: Yes, to get some games upgrades.

Me: Are those money also?

5:Yes. 

Me: But they are not coins and notes.

5: No, they are coins and notes if you send them to your bank, but inside the tablet they are just numbers.

Me: Ok, so money can be also numbers on the internet. Question: How many types of money they are? More than one?

5: Yes, more than one. We have pounds in England, We have euro when we go to Spain to holiday. We have dollars when we go to Disneyland in Florida. 

Me: So, we agree that there are different money in the world. Let say that almost every country has their own money with their own name. Do you understand all this stuff?

5: Yes. 

Me: Now, do you know what Bitcoin is?

5: Yes, Bitcoin is another kind of money that you can see watching different picture on the internet. 

Me: And do you know how do you use Bitcoin?

5: Yes, it is showing different numbers so you can shout in the house from time to time: Bitcoin is 10 thousand dollars, Bitcoin is 20 thousand dollars and so on. 

Me (laughing as i shout sometimes exactly like it was described): Yes, and because Bitcoin can be exchanged with dollars or pounds, Bitcoin is also behaving like money, but doesn't exists like coins and notes, in the real world, it is only on internet.

5: So Bitcoin is like internet money?

Me: Exactly. All the internet money, that doesn't belong to one country only, and do not exist in real world, are called cryptocurrencies. 

5: So, like dollar, pound, euro, if you said they are called, and not it is called, means they are many of them, with different names. 

Me: Yes, Yes. Exactly. They have different names like Bitcoin, Ethereum and in our case Ampleforth. This is the one i want to talk to you about. 

5: Oh oh oh, i know this one. 

Me (doubting): Do you?

5: Yes, it was a village near York, when we went to Moors National Park, we went through that village. We stopped there for ice cream. Remember? Now i am confused, you said only countries can make money. How is that a village has its own money?

Me (confused now): No, no, no. It is just that they got the same name, but got nothing to do with that village. Remember when we went in Romania, their money were called lions, but they got no lions in their country. 

5: But they did had a picture of a lion on the money. 

Me: Ok, so there is this cryptocurrency called Ampleforth, like the village, but it is not made in that village. 

5: Where it is made then?

Me: It is made online, on the internet, and exists only on the internet.

5: Who made it?

Me: Some people who learned who do make programs on the internet.

5: Oh, i know how to do programs on the internet. Yesterday on Scratch i made a cat who was walking and every two steps was saying meow. Listen, can i make my own money on internet, like a cryptocurrency, and i give it to you and you give me pounds instead? Can I?

Me: You can, in theory, but...

5: Then you need to show me. I will make a lot of them. At least 100. And i give you one at the time. And i can give one to gramma, one to grampa, even one to auntie. OH MY GOD! If i sell all of them with one pound each i can make £100. Can you imagine how do you feel having that much money?

Me (realising that explaining Ampleforth is harder than i tough): So, back to Ampleforth. This one is a bit different than the normal money..

5: Why?

Me (in obvious pain, as i need to research more in order to give a good answer): Do you know when i said that 5 years ago £100 would buy 140 euro, but now you can barely have 110 euro for the same amount. Why do you think this happened?

5 (smiling): Inflation. 

Me(puzzled): That is right, Inflation, do you know what that is?

5: No, but it was a bearded man on TV saying that inflation is why the money value change. 

Me: Ok. So Ampleforth. You know how Bitcoin and most of the other cryptocurrency can be exchanged with $1, $100 or even $10000. Their price is changing up and down. 

5: How many zero are in ten thousand dollars?

Me: 4, Why?

5: Because i did not know. Continue.

Me: So if you have 1 Bitcoin you can changed for $10,000 and maybe $15000 tomorrow, as the price change. 

5: Ok. 

Me: But Ampleforth is different. Imagine that the pet shop has 100 rabbits, and you pay to get half. That is 50 rabbits. But next day they have 200 rabbits, so half of it is 100 rabbits. The number does not matter, as long as you always have half of the rabbits from the shop. Did you understand?

5: No, this makes no sense. I understand that Ampleforth are internet money that are not like money, so why are they still money?

Me: Ok, let me try something else. (Going through my pocket) Here we have 10 coins of 1 pound. Let's say  this is online, and it is all the Ampleforth in the world. And i agree with you that you will always have half of all the Ampleforth in the world...

5:Like a contract?

Me:Exactly, this is called smart contract, and it is like a program on the internet counting your Ampleforth, giving you more if the total number increases, or taking some if the number decreases. 

5: Show me!

Me: Now we have 10 coins, so, half of it is 5 coins, that you get, as we agreed on the smart contract. But if i bring another 2 coins to the total, than i need to give you another coin, so you have 6, which is half of 12. If i take 8 coins out, and there are only 4 left as the total number, how many you will have?

5: 2 coins. 

Me: Exactly. And now is the funny thing. Lets say the total number of Ampleforth in the world is worth £100. Then your half, even if it is 2,5 or 6 coins it is worth ...

5: £50. I totally get it now. I understood. 

Me: Did you?

5: Yes i did, you are a great teacher. 

Me: Am I?

5 (going to his piggy bank): Now let's do that smart contract, i want to buy half of all the Ampleforth with £50. I can sell that to you and auntie and nana in exchange for pounds. I do not need to learn how to make my own cryptocurrency if there is one already made. I sell it when i have more only, and i wait for them to recover after. 

Me (really laughing): Half of the whole Ampleforth is not £50, we used 100 so you can understand. The real number is much higher. 

5: How much? I still want to buy.

Me: 241 millions is the total value. 

5:Millions?

Me: Millions

5: Then i don't want to buy it anymore.

Me: Glad I could help.

5: You didn't. You need to learn how to make my own cryptocurrency and give it all to me on my birthday. But make it simpler. Like Bitcoin. With a smart contract. One day after i give if to you or somebody else in exchange for pounds, my coins needs to come back to me. So i can make lots of money. 

Me: !?!?!