[colorint]

It's more of a technical note, but probably the last really important change was the accrual basis, which, as far as I know, was popularized in the 20th century. This is the system of accounting where you record revenues and expenses when you become aware of them, rather than when you pay them, so many things end up being recorded as debts. Notably, this is the currently-accepted way of doing accounting.

[cbr]

    this is the currently-accepted way of doing accounting

Cash basis is also accepted, and generally used by very small businesses where accrual accounting is too complicated.

[colorint]

Cash basis is accepted for the purposes of taxes, but my understanding is that it's not acceptable for legally-mandated reporting. That is, cash basis is not among the generally accepted accounting principles.