The address format used in Substrate-based chains is SS58. SS58 is a modification of Base-58-check from Bitcoin with some minor modifications. Notably, the format contains an address type prefix that identifies an address as belonging to a specific network.
Polkadot addresses always start with the number 1.
Kusama addresses always start with a capital letter like C, D, F, G, H, J...
Generic Substrate addresses start with 5.
The Pontem network uses the
5 prefix now. To be in compatibility with Diem we also support the Diem address format, it's 16-byte hex. For example, the Standard Library deployed using address
0x01. Pontem network reaches compatibility by converting SS58 addresses to Diem ones in background, by adding empty bytes to the address if necessary.