Provide a summary of Facebook's revenue sources in the fiscal year 2019.
In 2019, Facebook's main sources of revenue were advertising, which accounted for 99%, and fees from other services, which accounted for 1%. Advertising revenue mainly came from ads displayed in the news feed, Facebook's Instagram platform, and Messenger. Other services fees mainly came from WhatsApp subscription fees.
In fiscal year 2019, Facebook generated revenue of $55.8 billion, an increase of 28% from the previous year. The primary sources of revenue were advertising, which contributed $41.9 billion; other, which contributed $9.2 billion; and payments, which contributed $2.7 billion. Advertising revenue was primarily generated through mobile advertising, which accounted for $40.1 billion, or 71% of total ad revenue. Additionally, platform revenue from services such as Messenger and Instagram contributed $13.4 billion, or 25% of total revenue.  This revenue growth was driven by investments in product innovation and strategic acquisitions.