Double entry bookkeeping is very easy to understand once you ditch the ridiculous "accounting equation".
"Credit" means "source", "debit" means "sink".
Suppose you invoice a customer 10,000 euros. You now have a promise for 10,000 euros, but you account in dollars so it's a promise for 11,000 dollars at current exchange rates. So you credit the source, your "Income: Customer A" account ("income" and "expense" accounts represent the external world) $11000, and debit "Assets: Accounts Receivable" (an account for trade-credit promises like this) $11000.
Later, the customer pays your invoice, which gets you $10,500 because exchange rates have moved around. How do you account for this?
Your promise, which you accounted as $11000, is the source, so you credit Accounts Receivable $11000. You debit cash $10500, because you got $10500 in cash. Finally, credits and debits have to balance, so you debit "Expenses: Loss on Foreign Exchange" $500. (recall that "expenses", like "income", represents the external world, and you lost the other $500 to forex traders or whatever.)
Since you don't liquidate the business on any typical day of its operation, why would you attempt to figure out how that $500 fits into a hypothetical instantaneous liquidation when you could just... account for it by balancing credits with debits? (You do sort of instantaneous-liquidate when preparing financial statements, an infrequent task which is very mechanical compared to ledger entry.)
Well, this is hacker news, so a generous reading of the comment is that it is being mapped to semantics most of us here fully grok, and not as a general audience rewording for accounting.
Just because someone knows how to build a website doesn't mean they know anything about discrete electronics. I'd wager the majority of this audience doesn't. It's mostly software people.
"Credit" means "source", "debit" means "sink".
Suppose you invoice a customer 10,000 euros. You now have a promise for 10,000 euros, but you account in dollars so it's a promise for 11,000 dollars at current exchange rates. So you credit the source, your "Income: Customer A" account ("income" and "expense" accounts represent the external world) $11000, and debit "Assets: Accounts Receivable" (an account for trade-credit promises like this) $11000.
Later, the customer pays your invoice, which gets you $10,500 because exchange rates have moved around. How do you account for this?
Your promise, which you accounted as $11000, is the source, so you credit Accounts Receivable $11000. You debit cash $10500, because you got $10500 in cash. Finally, credits and debits have to balance, so you debit "Expenses: Loss on Foreign Exchange" $500. (recall that "expenses", like "income", represents the external world, and you lost the other $500 to forex traders or whatever.)
Since you don't liquidate the business on any typical day of its operation, why would you attempt to figure out how that $500 fits into a hypothetical instantaneous liquidation when you could just... account for it by balancing credits with debits? (You do sort of instantaneous-liquidate when preparing financial statements, an infrequent task which is very mechanical compared to ledger entry.)