How does google make money?
Google does provide services for free. You can say the model google follow is Freemium (Free + premium).
For example see below google search picture, you can see the ads on top of search results.
The other revenue channels for google are:
Adsense (the ad display window for adwords)
The major portion of income for google comes from advertisements. Google display advertisements on desktop, tablets, mobile everywhere.
The major products which generates revenue for google are:
Google rules the online market. Almost all blogging sites use the adsense for revenue generation, google takes 30% of the revenue generated. Google have a unique revenue model where it displays the ads on third party properties and share the revenue. The major products that displays the ads on third party property to make money for google are:
Youtube (Videos hosted by users are monetised and google takes upto 30%)
Blogs and websites (The ads we see on these sites are hosted by google under the brand name adsense, google shares 30% revenue)
Mobile Apps (Apps crafted in android are monetised by google, google takes the cut here too)
App sales on android (Apps hosted and sold on google play are traded through google, google charge a commission).