How many bitcoin addresses are possible?

The number of possible Bitcoin addresses is indeed staggeringly vast, and it far surpasses the estimated number of stars in the observable universe. This immense number is a testament to the cryptographic strength and security of the Bitcoin network. Here's an overview of just how massive the address space is:
 

1. Cryptographic Address Generation:

Bitcoin addresses are generated using cryptographic techniques. They are based on elliptic curve cryptography, which involves complex mathematical operations.
 

2. Address Format:

A standard Bitcoin address consists of a long string of alphanumeric characters, typically starting with a '1' (in the case of the original P2PKH address format) or 'bc1' (for Segregated Witness or Bech32 addresses). These addresses encode important information, including a public key and a checksum for error detection.
 

3. Address Space Size:

The total number of possible Bitcoin addresses is determined by the length and complexity of the cryptographic keys and the base used (typically, addresses use a base58 encoding). This results in an astronomical number of possible combinations.
 

4. Comparison to Stars:

Estimates suggest that there are around 100 billion stars in the Milky Way galaxy alone, and there are an estimated 2 trillion galaxies in the observable universe. This means there are around 200 sextillion (2 x 10^23) stars in the observable universe.
 

5. Number of Possible Bitcoin Addresses:

In contrast, the number of possible Bitcoin addresses is vastly larger. The exact number depends on the specific address format used and the length of the cryptographic keys, but it is estimated to be around 2^160 for the original P2PKH addresses, which is approximately 1.46 x 10^48 addresses.
 

6. Security and Uniqueness:

The vast number of possible Bitcoin addresses ensures the security and uniqueness of each address. It is practically impossible to generate the same address as another user.
 

7. Privacy and Anonymity:

The large address space also contributes to the privacy and anonymity of Bitcoin users. With so many possible addresses, it is difficult to link individual addresses to specific users without additional information.
 

8. Evolution of Address Formats:

Bitcoin has seen the evolution of address formats, such as Segregated Witness (SegWit) and Pay to Script Hash (P2SH) addresses, which offer additional security and efficiency benefits.