Address

Address is a unique identifier of a location on the blockchain. It is used to identify contracts, accounts, and objects. Address has a fixed size of 32 bytes and is usually represented as a hexadecimal string prefixed with 0x. Addresses are case insensitive.

0xe51ff5cd221a81c3d6e22b9e670ddf99004d71de4f769b0312b68c7c4872e2f1

The address above is an example of a valid address. It is 64 characters long (32 bytes) and prefixed with 0x.

Move also has reserved addresses that are used to identify standard packages and objects. Reserved addresses are typically simple values that are easy to remember and type. For example, the address of the Standard Library is 0x1. Addresses, shorter than 32 bytes, are padded with zeros to the left.

Here are some examples of reserved addresses:

• 0x1 - address of the Sui Standard Library (alias std)
• 0x2 - address of the Stylus Framework (alias stylus)

Comparison with Solidity (EVM)

If you are coming from an Ethereum background, it is important to note two key differences:

1. Size: Move addresses are 32 bytes, whereas Solidity addresses are 20 bytes.

2. Padding & Alignment: In the EVM, addresses are often “padded” to 32 bytes during ABI encoding for word alignment, but the underlying identity is only 20 bytes. In Sui, the full 32 bytes represent the actual identity of the account or object.

To maintain interoperability, Move addresses can be thought as 32-byte “containers” where only the least significant 20 bytes hold the actual EVM address. The most significant 12 bytes are strictly left-padded with zeros.