Debit and credit, without the jargon

Almost everything else in book-keeping falls out of one idea: money never appears, it only moves. Every entry therefore has two sides.

Books that write themselves from the bills

Aned Book Silver posts both sides from the document you already raised, so the ledgers, trial balance, profit & loss and balance sheet are a consequence of your billing rather than a second job. Basic is billing and inventory, without the ledgers.