All Questions

Filter by
Sorted by
Tagged with
48
votes
3answers
9k views

How does change work in a bitcoin transaction?

It seems that when you send a bitcoin transaction, all the coins in the sending address are spent in that transaction, divided into the amount that you intended to send, and "change", which goes back ...
47
votes
3answers
14k views

Will there be 21 million bitcoins eventually?

Every x blocks the mining reward is halved. Will the reward be halved forever such that we never quite reach 21 million bitcoins, or will we reach 21 million bitcoins at some point and will the reward ...
47
votes
5answers
27k views

What is meant by Bitcoin dust?

I've seen the term "dust" used to describe small transactions that might be considered as spam by the Bitcoin network. Is there is a generally accepted definition of this term?
46
votes
4answers
20k views

How can I accept Bitcoin donations on my blog or site?

If I sell things, there are many services that allow me to accept bitcoins as payment. But for those who simply want to accept bitcoins on their blog or other site ... as donations. A simple bitcoin ...
45
votes
6answers
6k views

What unique business models has Bitcoin enabled?

Are there specific, unique business models that have been made possible by the invention of Bitcoin? And if so, what are they? Edit: I seem to be getting a lot of answers about the areas of ...
45
votes
4answers
37k views

What are multi-signature transactions?

What are multi-signature transactions, and why might they be used? Also see: How does one make multisignature transactions with the bitcoin client? How can I create a multi signature 2-of-3 ...
45
votes
4answers
16k views

Why was the target block time chosen to be 10 minutes?

According to the wiki, 10 minutes was chosen as a 'tradeoff'. Why ten minutes specifically? It is a tradeoff chosen by Satoshi between propagation time of new blocks in large networks and the ...
45
votes
4answers
151k views

Import wallet.dat into a new Bitcoin-Qt client

I had Bitcoin-Qt on my computer with several bitcoins in my wallet, using Vista. Then my computer crashed. Finally I was able to get my computer fixed and download a new version of Bitcoin-Qt. Now I ...
45
votes
1answer
6k views

What do the different .dat files contain?

What data do different Bitcoin .dat files contain? How about the other files in the same folder? The wallet.dat file is somewhat documented and there are some ways to convert it to human-readable ...
44
votes
1answer
13k views

What are Channel Factories and how do they work?

One of the open research questions for Lightning Network is that it will take a massive amount of on-chain transactions to create enough payment channels for all the Lightning Network users. Lately, I'...
44
votes
8answers
17k views

Can bitcoin exist without miners?

In the past year only, the bitcoin mining difficulty has increased fivefold. If in the coming years the difficulty increases so much that mining is no longer profitable (i.e. consumes more power than ...
44
votes
2answers
9k views

What is the longest blockchain fork that has been orphaned to date?

The orphaned blocks view from BlockChain.info shows a recent fork of the blockchain (starting with block 173,928) that went four blocks long before being orphaned. Other than the controlled rewind ...
43
votes
3answers
12k views

Why does Bitcoin send the “change” to a different address?

For example I have an address (A) with 20 BTC and send 9 BTC to address (B). Bitcoin will create a "change" portion of the transaction where the remaining 11 BTC goes to address (C). Why not send ...
43
votes
10answers
9k views

How can I keep my wallet secure?

The standard Bitcoin client does not encrypt wallet files, so any malicious user that gains access to this file will be able to transfer all the coins to their own wallet. Furthermore, if I lose the ...
43
votes
5answers
8k views

How is Bitcoin supposed to serve as currency when it is all but impossible to spend at the moment (12/2017)? [closed]

It seems Bitcoin is not standing up to the test of use as currency (that is to say heavy use). I tried to pay someone 0.009BTC (about $150) for some goods which I need in a fairly timely manner. As if ...
43
votes
8answers
26k views

Is CPU mining even worth it? [duplicate]

I would like to start mining, but my GPU isn't the greatest and I don't really want to spend the money on a dedicated rig. Is mining from my CPU (in a Linux environment) still worth it? Or will I not ...
43
votes
1answer
12k views

How does Bitcoin Cash implement replay protection?

Bitcoin Cash says that they are providing replay protection for their fork. How does this replay protection work?
43
votes
2answers
14k views

What happens if two miners mine the next block at the same time?

The process of mining as described in the answer to this question is simultaneously repeated by multiple miners. Is it possible for two miners to find the next block at the same instant? If it is, ...
42
votes
1answer
61k views

Cryptocurrency Arbitrage - What do I need to know?

I'm curious as how one would go about arbitraging crypto currencies - How does it work? what do I need to look out for? What are the risks and caveats?
42
votes
6answers
21k views

Why is downloading blocks taking longer and longer?

First off, this really needs to get fixed. I'm downloading blocks for at least 8 hours now, and it's still not done. I know the problem of having to download the entire block chain is being worked on, ...
42
votes
3answers
27k views

How can I run bitcoind in pruning mode?

I read this comment: You could consider running a pruning node, which is practically the same as a full node (including security), except it throws away some of the old history. Version 0.11 ...
42
votes
2answers
60k views

What is a share? Can I find it while mining solo, or only when pool mining?

In mining, what is "a share"? When mining solo, do I "find shares"?
41
votes
7answers
92k views

Where are the user's bitcoins actually stored?

On the person's computer? On bitcoin.org? :) Where does that information reside that tells others and me how much bitcoins I have? I assume it can't be on my PC because I could easily hack the file ...
41
votes
4answers
48k views

How do I see the IP address of a bitcoin transaction?

How do I see the IP address that someone used to send or receive bitcoins with? Is it stored in the blockchain?
41
votes
5answers
27k views

What will happen to mining after the 20 999 999th Bitcoin?

After the 21 millionth bitcoin or 20,999,999th bitcoin is mined, what will happen to bitcoin mining? - will it just stop, or will we make a further division of the satoshi thanks to Bitcoin's infinite ...
41
votes
1answer
11k views

How are transaction hashes calculated?

I'm trying to calculate the hash of transactions in bitcoin blocks, but I'm not getting the right answers. For example, the genesis block has a single transaction. Here's how I'm attempting to ...
40
votes
2answers
6k views

What is the coin selection algorithm?

When creating a transaction in the standard client, what is the algorithm used to determine which unspent outputs will be used as inputs? Has this changed since the first version? What different ...
40
votes
7answers
51k views

How long would it take a large computer to crack a private key?

I am doing a presentation on Bitcoins and I was looking for some calculations to make people feel safe about the private key encryption. Please first answer, how long in bytes the private key is, ...
40
votes
2answers
5k views

How does Ripple solve the double-spend problem?

How does the Ripple system solve the double-spend problem? Does it also use some block-chain-like entity that officially dictates which transactions are confirmed and which are not, or does it use ...
40
votes
3answers
55k views

What's the difference between a wallet and an address?

Bitcoin seems to have the concept of a wallet and an address. Are they the same thing? If not, how do they differ?
39
votes
2answers
61k views

How can I export the private key for an address from the satoshi client?

If I want to transfer an address from the satoshi client into a different client, how can I find its private key to do so?
39
votes
4answers
57k views

Where is the data folder for Bitcoin-Qt?

Where can I find the blockchain, wallet.dat, etc. on each of the operating systems Bitcoin-Qt supports?
39
votes
2answers
11k views

What prevents a pool miner from stealing an entire block?

As I understand it,when mining BTC, and calculating a block, the goal is to find a SHA-256 hash below a certain value (with the previous block, a nonce, and other things as the input). Are pool ...
39
votes
3answers
10k views

How does the bitcoin client make the initial connection to the bitcoin network?

Once the bitcoin client is connected to a machine (or multiple machines) on the bitcoin network, they can share information (e.g. the block-chain, IP addresses of other nodes, etc). I understand how ...
39
votes
2answers
9k views

What are Green Addresses?

What are Green Addresses? Is it true that they can solve the "confirmation delay" problem, and how does that work? Are there any drawbacks?
39
votes
2answers
33k views

Do unconfirmed transactions expire?

Do they just sit there unconfirmed (e.g. when you be evil and don't pay a tx fee) forever? Or do they get deleted after a few days?
39
votes
5answers
2k views

How do I accept bitcoin payments at a real world store?

From what I understand, there are some requirements for using bitcoins at a physical store: Both the store owner and the client must have Internet access The client must have a cellphone or a laptop ...
38
votes
7answers
25k views

What happens if I mistype the address when making a payment?

I sent bitcoins to an address, but I think I made a typo when I copied it. Where did these bitcoins go. Can I get them back?
38
votes
3answers
14k views

What is a stealth address?

Stealth addresses are mentioned in the context of privacy of bitcoin transactions. What are they and how would they work? Can they provide 100% anonymity?
38
votes
3answers
43k views

Can I use my wallet on different computers?

I'm used to synchronize my data on different machines. Depending on the data I use SVN, Dropbox or SSH (Unison). Is this possible with the bitcoin wallet, too?
38
votes
3answers
5k views

Who runs www.bitcoin.org?

The original client that can be downloaded from www.bitcoin.org is often referred to as the "official client". Similarly many regard www.bitcoin.org as the "official homepage" of the project. So, who ...
37
votes
2answers
74k views

What is Gas Limit in Ethereum?

What is the function of Gas Limit parameter in Ethereum? Is it involved in mining or something else?
37
votes
5answers
6k views

How can one remain relatively anonymous while using Bitcoin?

Bitcoin transactions are pseudo-anonymous. What can an individual that uses Bitcoin do in order to remain as anonymous as possible?
37
votes
4answers
6k views

How is block-solution-withholding a threat to mining pools?

If I understand the technical process (for most mining pools) correctly, a participant in a mining pool is given block data to combine with a nonce to try to solve the block. If they get close (but ...
37
votes
8answers
4k views

How to save bitcoins as paper?

I would like to save some of my bitcoins on a piece of paper with QR code printed on it. What would be the easiest way to do it without using Mt Gox. or similar. Just bitcoins (I'm not afraid of some ...
36
votes
18answers
11k views

I paid in bitcoin, now I'm owed a refund. Can I demand it in bitcoin too?

This is, I suppose, a legal question so I should point out that I'm most interested in US and European law. I made a payment to a company for a product more than a year ago in bitcoin. The amount ...
36
votes
2answers
44k views

How do I import a private key into Bitcoin-Core?

How do I import a private key into Bitcoin-Qt? bitcoind is nowhere to be found, and pywallet says it requires "bsddb" when I run it, which is also nowhere to be found. I generated some vanity ...
36
votes
3answers
8k views

What are checkpoints?

I often read that checkpoints protect the network from a 51% attack because an attacker cannot reverse transactions made before the last checkpoint. How exactly does this checkpoint mechanism work? ...
36
votes
1answer
34k views

What are the bandwidth requirements of a mining rig?

How much bandwidth consumption can I expect per 900 Mhash/s rig (for instance) for both pooled and solo scenarios? I'm looking for a ballpark number for the on going requirements, after the initial ...
36
votes
2answers
9k views

Nonce size - Will it always be big enough?

If I understand correctly, the block only has 4 bytes (32 bits) for the nonce. Is it possible for the difficulty to become high enough that there are no nonce solutions? If so, then what options does ...

15 30 50 per page