How many bitcoin wallet address are there?

[Lomus]

Hello,
Does anyone know if there is a finite amount of bitcoin wallet addresses?

Also,

What stops a person generating the same bitcoin wallet address as one already in use?

- lom

[A+S]

Hello,
Does anyone know if there is a finite amount of bitcoin wallet addresses?

Also,

What stops a person generating the same bitcoin wallet address as one already in use?

- lom

Is a finite number, but it is really large. So in the practice is like it isn't finite.

Anyone can find a wallet with bitcoins but it will be like he finds life in another planet.... a miracle.

[AliceWonder]

For the addresses that start with a 1 there are theoretically 2^160 possible addresses.

That's a really big number.

When two people get the same address it is called a collision.
When it happens it almost certainly means the private key was generated from a weak brain wallet and not high entropy random data.

[DannyHamilton]

Hello,
Does anyone know if there is a finite amount of bitcoin wallet addresses?

Finite?  Yes.  However, be aware that the quantity of possible addresses is astronomically large. It is so large, that the average person has a difficult time with the concept and then, unfortunately, has unrealistic concerns.

Also,

What stops a person generating the same bitcoin wallet address as one already in use?

- lom

Probability.  It is so unlikely, that it doesn't need to be a concern.  You have a better chance of being stuck by lightening every year for the next 10 consecutive years than you do of encountering a bitcoin address collision.  How much time do you spend worrying about the possibility that you might get struck by lightening every year for the next decade?

[AKCoins]

For the addresses that start with a 1 there are theoretically 2^160 possible addresses.

That's a really big number.

When two people get the same address it is called a collision.
When it happens it almost certainly means the private key was generated from a weak brain wallet and not high entropy random data.

What happens when there is a collision? What is the potential outcome of this scenario?

[keatonatron]

For the addresses that start with a 1 there are theoretically 2^160 possible addresses.

That's a really big number.

When two people get the same address it is called a collision.
When it happens it almost certainly means the private key was generated from a weak brain wallet and not high entropy random data.

What happens when there is a collision? What is the potential outcome of this scenario?

What happens? We can't answer that, because it has never happened before 

Not with randomly generated addresses, that is.

All collisions so far have been either intentional (i.e. stolen keys [passwords]) or by carelessness (someone generating an address from an easily repeatable key [password])

[DannyHamilton]

For the addresses that start with a 1 there are theoretically 2^160 possible addresses.

That's a really big number.

When two people get the same address it is called a collision.
When it happens it almost certainly means the private key was generated from a weak brain wallet and not high entropy random data.

What happens when there is a collision? What is the potential outcome of this scenario?

The outcome of the scenario is that both people who have generated the address from a private key that they control have access to any bitcoin that are sent to that address.  Whoever of the two of them sends the bitcoins somewhere else first will see their transaction succeed.  Then the other person will see the bitcoins simply vanish from their wallet.

[niko]

For the addresses that start with a 1 there are theoretically 2^160 possible addresses.

That's a really big number.

When two people get the same address it is called a collision.
When it happens it almost certainly means the private key was generated from a weak brain wallet and not high entropy random data.

What happens when there is a collision? What is the potential outcome of this scenario?

Strange things happen when a collision takes place. Stranger than being struck by a lightning once a year, for ten years in a row. See above. Do the math. Try some comparisons. Please.

[inceptor]

is there limit one person can have how many BTC addresses?

online ewallet safe to use? or most better bitcoin use on local pc?

[niko]

is there limit one person can have how many BTC addresses?

online ewallet safe to use? or most better bitcoin use on local pc?

The only limit is how fast you can generate them from private keys.  See "vanitygen" for example.

It's off-topic, but online wallets are as safe as the owner is trustworthy and competent. People here will usually yell "trust nobody!" by default, but it's not as simple. In some areas I trust my own skills less than those of certain individuals behind certain companies. You need to decide for yourself. Just keep in mind that some online wallets fully own and control (and risk) the private keys to your coins, whereas some services store private keys on your local machine, and only take care of the blockchain management for you.

If you decide to run a local "full" client, plan on leaving that PC on all the time, plan on waiting up to several days for the initial sync, and plan on having lots of disk space.