<p>Ok, you can create your own <strong>private</strong> blockchain. It will be visible only by yourself. Nobody will not even know about it. I do not see any reason for it, but you can call it "blockchain" if you want. You can call it "my private blockchain" or even give any name for this technology, for example "nsdfuishgreryuiw"</p>

CC BY-SA 4.0
2018-08-26T14:52:38.407Z
Consider a company or organization which aims at using (permissioned) blockchain such that it is visible only for its (internal) employees. So, it uses ex. visibility of blockchain but limited only to internal employees.
Questioner
CC BY-SA 4.0
2018-08-26T14:04:28.283Z
2018-08-26T14:04:28.283Z
amaclin
<p>Their are two kinds in blockchain </p>

<ol>
<li>Permission less</li>
<li>Permission-ed </li>
</ol>

<p>In Permission less blockchain (Bitcoin) it's public. And anyone can join network.
In Permission-ed blockchain (Private company) ,participants are known and it may not be public to everyone.</p>

CC BY-SA 4.0
2018-09-06T15:01:16.013Z
2018-09-06T15:01:16.013Z
VforVendetta
<p>In regards to bitcoin, yes, the blockchain is always public. The reason behind it is that it needs to be. Without having public access to the bitcoin blockchain the whole system would not work. A miner for example could not verify pending transactions because how would he know if they are valid or not without checking the blockchain? The public blockchain is a part of what makes bitcoin so special - without it, bitcoin would not be a decentralized network. You would need a central authority which manages the blockchain and keeps it private, just like a ... bank.</p>

<p>So in conclusion, the blockchain need to be accesible to everybody who <strong>wants to take part</strong>. As bitcoin wants everybody to be able to take part, everybody needs access to the blockchain.</p>

CC BY-SA 4.0
2018-08-26T15:50:55.623Z
Thank you, but my question is, in general, `blockchain` and not necessarily `Bitcoin blockchain`.
Questioner
CC BY-SA 4.0
2018-08-26T15:53:05.417Z
If you could extend your question and describe what you are actually trying to achieve we might be able to help you more.
Bobface
CC BY-SA 4.0
2018-08-26T16:00:27.883Z
I edited my question. My main question is about correctness of proportion of blockchain wikipedia page (i.e. blockchain is alway a public ledger?) and permissioned blockchain.
Questioner
CC BY-SA 4.0
2018-08-26T16:04:26.463Z
Well of course you could deploy some kind of "private blockchain technology" inside a company. But why not simply use the existing and working system?
Bobface
CC BY-SA 4.0
2018-08-26T16:27:35.440Z
It's not my purpose, but also I want to be sure that if the existing definition of blockchain in its wikipedia page is correct? Is a permissioned blockchain public ? The fact that deploying a private blockchain is logical or not is another question. The question is definition of a blockchain.
Questioner
CC BY-SA 4.0
2018-08-26T16:36:06.133Z
By the pure technical definition: no, a blockchain does not need to be public. It must however be accesible to everybody who wants to take part in the system. The reason why the wikipedia page says it is public is because there they are talking about real world applications like bitcoin.
Bobface
CC BY-SA 4.0
2018-08-26T16:45:42.230Z
OK, but the page is not about only Bitcoin BC, but also it defines **generally** the BC. From my point of view, to have an **immutable** BC, we need the blockchain to be **maintained** by a **decentralized consensus**, otherwise in case of using ex. PoA and permissioned approach, since it's a centralized approach, there is no **guarantee** for a BC user that in future what happens for the BC and if the BC **will exist** after years? So, in this case, there is no guarantee for existing transactions history in future. And   at this point question is **why** do we use such a blockchain?
Questioner
CC BY-SA 4.0
2018-08-26T18:32:30.380Z
blockchain is not immutable
amaclin
CC BY-SA 4.0
2018-08-26T19:15:38.553Z
@amaclin It depends on which consensus mechanism we use. ex. in case of using PoA, if pre-selected validators decide to change/remove the whole of blockchain, it's possible. When we talk abut blockchain, we don't talk necessarily talk about Bitcoin blockchain. Meanwhile, do you mean action history? and if so, blockchain is not reliable anymore.
Questioner
CC BY-SA 4.0
2018-08-26T15:47:03.910Z
2018-08-26T15:47:03.910Z
Bobface
<p>I think the 'public' in this definition is not equals to the 'public' for public blockchains.</p>

<p>We may consider whether a blockchain is public in these points:</p>

<p>1, If anyone can read it;</p>

<p>2, If anyone can join and become its user freely;</p>

<p>3, If anyone can add blocks on it.</p>

<p>For public blockchains like bitcoin, the answers are all yes. If for some blockchain, some answers are yes and some are no, it is not easy to say if it is public. </p>

CC BY-SA 4.0
2020-01-26T15:06:36.707Z
2020-01-26T15:06:36.707Z
saintthor
<p>Is the following <strong>definition</strong> of <strong>blockchain</strong> by <a href="https://en.wikipedia.org/wiki/Blockchain#Structure" rel="nofollow noreferrer">its wikipwdia page</a> correct?</p>

<p>Where it is mentioned:</p>

<blockquote>
  <p><em>A blockchain is a decentralized, distributed and <strong>public</strong> digital ledger
  ...</em></p>
</blockquote>

<p>Cannot we have a private blockchain? And if so, is the above proposition wrong ? when it says <strong>always</strong> a blockchain is <strong>public</strong>.</p>

<p><strong>An example:</strong> Consider a company or organization which aims at using (<strong>permissioned</strong>) blockchain such that it is visible only for its (internal) employees. So, it uses ex. visibility property of blockchain but limited only to internal employees.</p>

<p><strong>Please Note</strong> that here the question is NOT if using a permissioned blockchain is logical or not, but also the question is the exact definition of a blockchain. So, according to definition of blockchain in its wikipedia page, a permissioned blockchain is real blockchain?</p>

<blockchain><terminology><decentralization>
Is blockchain always "public"?
Questioner
# Is blockchain always "public"?

(Asked by: username_0 on 2018-08-26)

Is the following **definition** of **blockchain** by [its wikipwdia page](https://en.wikipedia.org/wiki/Blockchain#Structure) correct?

Where it is mentioned:

> *A blockchain is a decentralized, distributed and **public** digital ledger
> ...*

Cannot we have a private blockchain? And if so, is the above proposition wrong ? when it says **always** a blockchain is **public**.

**An example:** Consider a company or organization which aims at using (**permissioned**) blockchain such that it is visible only for its (internal) employees. So, it uses ex. visibility property of blockchain but limited only to internal employees.

**Please Note** that here the question is NOT if using a permissioned blockchain is logical or not, but also the question is the exact definition of a blockchain. So, according to definition of blockchain in its wikipedia page, a permissioned blockchain is real blockchain?

**Tags:** blockchain, terminology, decentralization


---

## 4 answers

### Answer by username_1 on 2018-08-26. Score: 1

Ok, you can create your own **private** blockchain. It will be visible only by yourself. Nobody will not even know about it. I do not see any reason for it, but you can call it "blockchain" if you want. You can call it "my private blockchain" or even give any name for this technology, for example "nsdfuishgreryuiw"

> **Comments:**
> **username_0**: Consider a company or organization which aims at using (permissioned) blockchain such that it is visible only for its (internal) employees. So, it uses ex. visibility of blockchain but limited only to internal employees.  

---

### Answer by username_2 on 2018-09-06. Score: 1

Their are two kinds in blockchain

1. Permission less
2. Permission-ed

In Permission less blockchain (Bitcoin) it's public. And anyone can join network.
In Permission-ed blockchain (Private company) ,participants are known and it may not be public to everyone.


---

### Answer by username_3 on 2018-08-26. Score: 0

In regards to bitcoin, yes, the blockchain is always public. The reason behind it is that it needs to be. Without having public access to the bitcoin blockchain the whole system would not work. A miner for example could not verify pending transactions because how would he know if they are valid or not without checking the blockchain? The public blockchain is a part of what makes bitcoin so special - without it, bitcoin would not be a decentralized network. You would need a central authority which manages the blockchain and keeps it private, just like a ... bank.

So in conclusion, the blockchain need to be accesible to everybody who **wants to take part**. As bitcoin wants everybody to be able to take part, everybody needs access to the blockchain.

> **Comments:**
> **username_0**: Thank you, but my question is, in general, `blockchain` and not necessarily `Bitcoin blockchain`.  
> **username_3**: If you could extend your question and describe what you are actually trying to achieve we might be able to help you more.  
> **username_0**: I edited my question. My main question is about correctness of proportion of blockchain wikipedia page (i.e. blockchain is alway a public ledger?) and permissioned blockchain.  
> **username_3**: Well of course you could deploy some kind of "private blockchain technology" inside a company. But why not simply use the existing and working system?  
> **username_0**: It's not my purpose, but also I want to be sure that if the existing definition of blockchain in its wikipedia page is correct? Is a permissioned blockchain public ? The fact that deploying a private blockchain is logical or not is another question. The question is definition of a blockchain.  
> **username_3**: By the pure technical definition: no, a blockchain does not need to be public. It must however be accesible to everybody who wants to take part in the system. The reason why the wikipedia page says it is public is because there they are talking about real world applications like bitcoin.  
> **username_0**: OK, but the page is not about only Bitcoin BC, but also it defines **generally** the BC. From my point of view, to have an **immutable** BC, we need the blockchain to be **maintained** by a **decentralized consensus**, otherwise in case of using ex. PoA and permissioned approach, since it's a centralized approach, there is no **guarantee** for a BC user that in future what happens for the BC and if the BC **will exist** after years? So, in this case, there is no guarantee for existing transactions history in future. And   at this point question is **why** do we use such a blockchain?  
> **username_1**: blockchain is not immutable  
> **username_0**: @username_1 It depends on which consensus mechanism we use. ex. in case of using PoA, if pre-selected validators decide to change/remove the whole of blockchain, it's possible. When we talk abut blockchain, we don't talk necessarily talk about Bitcoin blockchain. Meanwhile, do you mean action history? and if so, blockchain is not reliable anymore.  

---

### Answer by username_4 on 2020-01-26. Score: 0

I think the 'public' in this definition is not equals to the 'public' for public blockchains.

We may consider whether a blockchain is public in these points:

1, If anyone can read it;

2, If anyone can join and become its user freely;

3, If anyone can add blocks on it.

For public blockchains like bitcoin, the answers are all yes. If for some blockchain, some answers are yes and some are no, it is not easy to say if it is public.


---

