How do websites make money and why are they worth so much?

-I never understood how websites are worth so much money, I.E. Facebook and Google. they are worth millions and millions of dollars so can anyone tell me where they get there worth from?Advertisements and investment buyersThe reason they are 'WORTH' billions of dollars is because they know EVERYTHING about you. Often, more than what you know about yourself. Everytime you click that 'Like' button on Facebook, it is stored in their database. So now facebook knows what you like, your interests, where you go, where you live, your age, and tons of things.... Google, saves your web browsing data on their servers and also your e-mail if you use Gmail. So they scan all of your data and keep it, so that they know who you are and use this data to sell you things and etc. They know everything about you.



How they monetize this information? In different ways, many of which we never see. However, the monetizing method they use that we partake in is usually Advertisements.