Books of account are opening by means of a principal journal.
The principal journal is also known as the general journal and is used to record transactions that cannot be recorded in other specialized journals such as the purchases journal or the sales journal. It is the first book of entry where all transactions are initially recorded, including opening entries for assets, liabilities, and equity accounts.
In other words, the principal journal is used to record transactions that do not fit into any other journal. These transactions include the purchase or sale of fixed assets, adjustments, and other types of transactions that are not part of the normal day-to-day operations of the business.
Therefore, the principal journal is used to open the books of account by recording the initial transactions in the accounting system.