It's called RBF

I've just sold a .com for $2,000. I offered it to the guy for 5 bitcoins, and that was before the recent price increase. He decided to stick with dollars though. I must admit that I prefer .com extensions - JetCash.com is mine for example, and I plan to use that to promote crypto currencies.

You should be able to do something with "bitcoin website" to get some SEO, so you should be able to earn a profit on reg fee. ( although $30 seems a bit expensive if that is the cheapest fee).

The added bandwidth demand comes from Microsoft, Google and other clouds, and from them copying and storing our data for the US government. A bit of extra traffic for a relatively small application like Bitcoin won't make much difference.

What if banks didn't have a central processor, but used each branch as a node for their own distributed processing? Of course that would be an alt currency, but it could get government support. If the gov. was one of the nodes, they could oversee everybody's accounts. Wouldn't they love that.

But if it doesn't receive a valid block based on its last good ones, but continues to receive blocks based on the apparently bad block, is that the start of a hard fork? Can the node do anything at that stage, or must it update to be able to accept the new blocks?

I'm running the latest version of Bitcoin core, and I understand that this is good for the community because I am validating transactions. I'm not mining, so I'm not creating blocks. Now, what happens if I download a block, and I find that it contains an invalid transaction? Obviously, I can reject the block, but then what? At that point my blockchain has terminated. There doesn't seem to be a way for me to communicate the error with anybody. Do I just sit and wait for a miner to build another block based on the last valid one that I was given? What happens if I don't get anything based on that block?

Thanks for that clear description of transaction handling, and the UTXO pool. The pool handling was going to be Forking Q3, but I think I understand how transactions get accepted and rejected now. Also, I can see how transaction fees can influence the miner.

I had to read your post two or three times, thanks for that.

One thing that I hadn't thought about is this - at any one time, there is always a latest block on the blockchain ( assuming no forks ). Am I correct in assuming that all miners are hitting on that to create the next block? When they find a block, it is then a race to get your new block hitched to that block. At this point, all the other miners give up on their current transactions, and start hitting on the new block. Are there multiple solutions to the calculations based on the same block?

Sorry about my limited knowledge of cryptology. I was a commercial programmer, and at that time, CRC was the advanced stuff.

They are called side chains.

I'll run a full node for Bitcoin, and probably full nodes for a couple of alts. That's using public WiFi as well.

Start a thread on Bitcointalk - that seems to work.

I thought the SPV miners didn't bother to verify transactions.

Following on from Q1, I'm not sure what happens in the case of an unconfirmed transaction that is subsequently found to be invalid. I gather that this invalidates the whole block, and therefore any subsequent blocks. Is this correct? I believe that some miners use unconfirmed transactions to get their blocks out faster. I guess this means that the chain backs up to the block before the invalid block. Now I'm starting to get lost.
Will miners still be using that block as a basis for their PoW, or will they have moved on to the later ( now discarded ) blocks?
Will careful miners who have been validating the transactions in the dodgy block, be at an advantage when they submit their next block if they use the earlier (valid) block?
What happens if the dodgy block was one that created an orphan - will that orphaned block be adopted by the careful miner who found the dodgy block?

Thanks for that explanation. I think I understand now. Bit of a bummer to do all that work and lose it because you were a micro-second too late, but I guess that's life.

Why can't the miner use the PoW for the orphaned block to create a completely new block to add to the current longest chain? If that PoW hasn't been used in the current chain, then surely it can be retried.

I'm having difficulty in understanding the full complexity of blockchain forking. Most explanations seem to incorporate a variety of problems and descriptions, and this is making it difficult for me to understand. With your tolerance, I would like to ask a number of questions about specific forking issues, and I hope this will allow me to build a clearer picture of the issues. This first question is the relatively minor issue of orphaned blocks.

Sometimes a couple of miners will find a new block at virtually the same time. They both add these blocks to the chain, and this creates a chain with two "heads" but the same tail. As other miners find blocks they add their blocks to one of the heads, and this locks the direction of the chain if it becomes the longest. The other head ( and any blocks following it) are left out in the cold, and are described as orphaned blocks. Is this description correct? This leads to another question - what happens to those blocks? Are they discarded, which means the miner loses the revenue from his PoW, or can the miner re-use them and add them to the new longest chain? What happens to the transactions in them? Do they go back into the pool, and what if some have been included in new blocks? ( is this possible? ).

I didn't know you had found my coins - please can I have them back.

signed

Franken ( Ein Stein's younger brother)

The US sancions seem to be harming the US more than other countries. I gather 20 countries responsible for around 60% of world trade no longer use the dollar for international settlement. The latest seems to be the switch to the Euro for trade between Iran and Brazil. In fact the lucrative emerging Iranian trade with other countries is now based on the Euro. This follows the strengthening of the Russian banking system, and the increased availability of internal Russian finance following US sanctions and the withdrawal of the dollar back to Russia, and the creation of the AIIB following US IMF policies against China.

Do you think this will create some additional growth for Bitcoin?

The timing of anything to do with Bitcoin that includes the word "stealth", seems most unfortunate at the moment.

I think it's America that's in trouble, not Bitcoin. Bitcoin is here to stay - embrace it, or slip further back in world trade. The US has got one of the worst banking systems in the world, you still have to rely on cheques for some international funds transfers. They tried to screw the Russian banks, and this caused the re-patriation of US dollars by many Russian businesses. This has strengthened the Russian banking system, and provided funds for investment in Russia. The US needed to keep those dollars, but politicians with myopic political views don't seem to understand the results of their actions. Their attacks On the Bitcoin concept is yet another example of this lack of knowledge and common sense.