Hi I was going through Solidity documentation more specifically accounts section, I understand that there are two types of accounts in Ethereum one is External accounts (the one owned by the human) and other is contract account which store code.

Both types of account can hold ether but one line in documentation confuses me

Every account has a persistent key-value store mapping 256-bit words to    256-bit words called storage.

Here is the link of the documentation http://solidity.readthedocs.io/en/v0.4.24/introduction-to-smart-contracts.html#index-6

I understand how contract have storage space and why, but why this line is applied for the External account? There are answers available in the context of contract accounts but not in the context of an external account.

Am I missing something here? Any help would be highly appreciated and will be helpful for me and for future readers.


Accounts have a common data structure, so technically you can say that both externally-owned accounts and contracts have a code section and a storage section. However, for externally-owned accounts both code and storage are empty. There's no way to write to the storage of an externally-owned account.

  • If storage and code section of external account is empty then why provide them space in the first place? Don't you think it is waste of hard disk space? – Thinker Jun 26 '18 at 10:50
  • It gives you a common data structure for externally-owned accounts and contracts, which makes things simpler. – Edmund Edgar Jun 26 '18 at 10:53
  • Ok, they both have common data structure but storage and code field in case the external account is set to empty. – Thinker Jun 26 '18 at 10:56
  • 2
    Storage is represented as a trie, so an empty storage takes essentially no disk space, only nonzero entries require space – Tjaden Hess Jun 27 '18 at 2:53

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