Define the term 'Book of account' as per the Companies Act, 2013.

According to section 2 (13) of the Companies Act, 2013, 'Books of account' includes records maintained in respect of: (i) all sums of money received and expended by a company and matters in relation to which the receipts and expenditure take place; (ii) all sales and purchases of goods and services by the company; (iii) the assets and liabilities of the company; and (iv) the items of cost as may be prescribed under section 148 in the case of a company which belongs to any class of companies specified under that section.