You have a minor grammatical mistake in the following sentence: <blockquote> The next time a new block gets produced, the block producer will have to chose which of the chains to append the next block to.</blockquote> It should be <i>to choose</i> instead of <i>to chose</i>.

That's interesting, it's really cool to see how different steem and bitcoin are! I really feel like steemit, and the steem blockchain is much better than bitcoin's.

Very enlightening I must say. The system is way more complicated than the "blogging platform built on a blockchain" front and there's a lot of research and programming skill required. Does the fact that steemit blockchain has a more advanced mining protocol than most mean that the value is inevitably going to rise sky high?

This is an excellent explanation of "Double Block Producing" and much easier to understand now..

I learned something new from this also, I never knew in the early days that SP could be taken from a witness for double producing..  Very interesting..
I can see how that illustrates just how important it is to not double produce blocks.

Thanks for this @timcliff

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Also, witnesses should be extra vigilant when doing maintenance, migrating/adding servers, generating new key pairs. Although they may not be malicious, the common mistake is to use the same key pair on two servers, which results in double producing.

So, always disable your witness when doing maintenance by broadcasting this key `STM1111111111111111111111111111111114T1Anm`, and triple check that the keys are **different** on **every node**. Re-enable the witness with the main server node's key when all is good and keep an eye on the logs until the next produced block is OK.

Here's an example of a double production (collision):

`1560475ms th_a       database.cpp:538              _maybe_warn_multiple ] Encountered block num collision at block 22296845 due to a fork, witnesses are: [["steem-bounty","2018-05-10T03:26:00"],["steem-bounty","2018-05-10T03:26:00"]]`

Note that if the collision happens between *two* witnesses, it's often due to a temporary lag, for example:

`28220ms th_a       database.cpp:538              _maybe_warn_multiple ] Encountered block num collision at block 22214744 due to a fork, witnesses are: [["netuoso","2018-05-07T07:00:24"],["xeldal","2018-05-07T07:00:27"]]`

Notice the timestamps with exactly 3 seconds difference.

Good and short explanation. Thank you @timcliff

Woah ! I definitely have to read this more than once. Cue airplane over my head :) So much to learn. What a layered beast all of this is.

The whole concept of Witness work involves not only votes and SP weights, but some common ethics to help the platform rather then acting maliciously. The unfortunate event of 'trading / begging' etc for Votes makes a ground for ill intended people to achieve high positions in Witness list.

Lately I noticed many votes coming towards my Witness, that simple got removed after a couple of days. The way i see it, is because of not approving back. (and I am not approving back, because too many missed blocks / compared to position as a main reason).

I would only say it's our mistake for offering tons of simplified solutions suck as docker allowing everyone to become a witness,  then execute different strategies (of questionable ethics) to claim high.

As simple as that, someone with enough knowledge to compile and run nodes from scratch is assumed to have enough knowledge to make money outside the scope of abusing the platform.

Witness work is not for everyone. Making it easy for everyone to join the race will only bring trouble.

Thank you @timcliff, you have described a very important issue in a way that everyone understands, it is very valuable. I would like to ask for more ;-)

Wow... I just can’t hold that wow. This is amazing , this is comprehensive , It felt like reading a white paper . Thanks for this much education and information. 

>Blockchain 101 - Why double producing is bad

I like the sound of this. I look forward to further courses

That was somehow a good recap of the blockchain consensus and double spending problem, and same time a good lesson of history of Steem. 

I just tried to contribute to Steem github and saw your comment, thanks for the review! If you have time, could you give me some information about how (or if) should jenkins be ran on external branches?

Sorry to bother you, and thank you so much!

Thank you for the indepth yet easy to follow  explanation of blockchain and witnesses. I have a much better understanding after reading your post. Double producing definitely sounds like it could be a serious issue. If the ability to remove the SP of someone one guilty of this is turned off, how is a witness who gets caught penalized?

This is why i follow you, i will have to read that again to fully understand it though lol...

First of all, I have to say that I am extremely happy that I decided to follow you. The first time that I met you was during your post on raising the dust vote amount. So, I'll just come out and tell you the truth, I really only followed you so that I can keep up with any more crazy ideas that you might have. Now, however over the course of the last week or so, I am really beginning to realize that you're doing the best you can try to think of ways to solve problems here. Not only that, but you're probably one of the smartest guys and I've met here and my short time. So, I would like to thank you once again for what you're doing. And like I said last time, you deserve to be paid for your work, so I am hoping that you will accept payment for this post. And I have been thinking about this since the last time. You could take, say half, or any amount you decide, and just hand it out to people in the community who you deem Worthy or that need it. Or however you would seem fit, it's your money. Just an idea to throw out there. Now, on to this post. This is probably the best, simple, explanation of the blockchain that I have ever heard. And I appreciate you for the simplified explanation that you offer. I also think that it is a great thing that you explain the potential issues with double producing. And as far as how easy it is to be able to become a witness due to the simplified processes, I never realized that this was the case. To me, I agree with you, and I think that this is a serious potential for abuse. And while they removed the old punishment, have they not installed any new form of punishment for double producing? And also, is there any way that you guys(witnesses) keep track of this, so that if it does begin to happen it can be stopped quickly? Or is it something that potentially could be hidden until it caused a serious Fork? I ask you these questions because lately as I have gotten deeper into the steemit "behind the scenes" there are a lot of things that concern me. When I first arrived here, I thought everything was happy-go-lucky. I now know that this is not the case. I have enough concern that I have stopped investing my own personal money, and have only been gaining money and SP here through authoring and curation. I appreciate any response that may be given in regards to my questions. And I would like to tell you to keep up all of your great work. I think that you were doing good stuff here and I believe that you deserve encouragement. So thank you so much again for what you're doing and I hope that you have a wonderful week. As always I send you and all of yours all my love until we meet again.

woo this is very educating, to get the complete information i think i have go through it over and over, to many sheet story about this mining this this is helpful thank for the information.

Very interesting information with very good graphics thank you friend for this great contribution good greetings

Thank you @timcliff for such a comprehensive explanation focussed on Double Producing.
 Few questions,
1. How could whistleblower or some other witness take all the SP, how does that work in the backend?
2. Is the problem limited to dPOS or we have such problem in POW as well, If yes how it works on it?
3. Trying to learn something about blockchain.. you mentioned that the data entered before a block is produced remains static, again trying to clarify how does that work in the backend, is it Merkle Trees and Hashes?

hi @timcliff, as a new witness I have so much to learn and thankfully people like you educating.  found the post very informative and easy to understand (for the non tech. like me) and some of the comments also added value

Wow, very explainable and easy to understand. Thanks for sharing

hello, sir how can I catch you on discord channel? we have one channel with 700 members we are trying to make nice project and help to steem community and we have the nice idea for it and we need you to be the witness of our project and we need your support is our discord channel https://discord.gg/3HZdaGk we will explain for you about our project and we are trying to make introduction post about and we need your advice

Hi Tim, I know I.m on steemit for quite some time now but it.s first time i saw your interview and I just want to say thank you and i agree 100% with what you said because that.s what I discovered too in my steemit journey. Here is the link towards your interview which I saw https://steemit.com/blog/@terrybrock/steemit-success-series--timcliff-on-who-to-target-with-your-content-1512178826-124805 , thank you again and i hope our paths will cross one day. I wish you a great day and much luck! Alina

This was extremely well written and explained lay-person style. Not a lot of devs can do that, nor do they take the time to try.  Thanks!

Hello, I have followed you and got votes on Steemit, be kind enough to follow me. Let's create a great community. Thanks & Best Regards