ratio of gross profit to sales So what are these three factors? They are Cost-Per-Click's (CPC's); which is the sum of money Google pays in the market to a publisher after their ads are clicked by way of a visitor. Click-Through-Rates (CTR's); which is a percentage figure showing frequent AdSense ads are clicked divided by the quantity of unique visitors passing by having a particular site and also the third essential factor is traffic levels. Edwards and bell's point of view The accounting income follows the historical cost principle and the matching principle, which is conducive to the objective reflection of the business management responsibility of the enterprise management authorities. But, due to the historical cost principle inherent defects, especially according to the present value of revenue and expenses by historical cost line, makes the calculation of accounting earnings lack of inner logical unity, and the matching principle is difficult to carry out, so that the book value of assets can not reflect its real value, cost cannot be fully compensated. And the economic benefit is measured in the current value, which reflects the actual value of the asset, which is beneficial to the full compensation of the cost. Mooney and si prowse in its around the main accounting principles for enterprises ", not only emphasize to determine profits in a timely manner, and emphasizes the necessary through division operating earnings, the gains and the impact of price changes, to improve the comparability of financial statements and understandability. In the 18th century, the western countries successively carried out the industrial revolution, the universal adoption of large machinery, laid the foundation for the establishment of factory system. In 1771, British man Richard arkwright1732-1792 founded the first cotton-yarn factory in the city of kron. In the 1930s and 1940s, the factory system was established in Britain, Germany and other countries. The main sex of factory system is: to carry out large-scale intensive labor; Using big machine to improve efficiency production; Implement the employment system; The division of labor is deepening and production is socialized. The establishment of factory system marks the real birth of enterprises.