How do free image hosting servers make money?

Nowadays there are at least a dozen websites with native apps for iOS and android that offer free online storage (ranging from 3 GB to 10 GB) to store/upload/sync your phone camera's photos.

I was wondering what benefit do they get by offering us the free storage space? I really hope they're not going through my photos to look for saleable photos and use them as stock photos to make a profit?

what exactly is the motive of free online storage servers behind attracting people to opt for their storage service? Like, i have 10 GB of storage space in my OneDrive (formerly SkyDrive) which I think is way too much more than what i'll ever need. If I do the math, an 8mp photo from iPhone 5 weighs in between 1 MB and 1.5 MB, and that divided by 10 GB gives me the capacity to store around 6700 photos in OneDrive which is good enough for storing photos for upto one year (18 photos each day every day). And most probably, no matter how deep inside the jungles of Africa, or high above the peaks of Andes and Himalayas I live in, I will get access to a computer with my own personal backup drive at least once within that period of time, when I could sync my photos to computer and save them in hard drive/dvds for storage.

now, during the above mentioned process, at what point does the Microsoft OneDrive make money? Is it only about the number of users you have? Or the boasting about petabytes of storage capacity you have in your servers? Or is there another (wicked) notion behind it? Like to compile a database of as many people as possible, where they go, what they do, where they hang out etc?

Well they do it through affiliate marketing. Almost every of such website or servers whatever you may call it have advertisements along with the content. Through these advertisements they create money. Else they also offer paid or something like premium memberships and it costs you some amount right? But basically they earn through affiliate marketing. For instance if you click those ads, its a unique click and they earn some amount. If you purchase a product by clicking that advertisement again they earn a certain commission. This is called pay per click, pay per lead, or Cost per Action type programs.

There are lots of affiliate program sites basically Google Adsense and Commission Junction etc, they offer such programs and that too, for free! So these website owners register with them copy and paste ad. Codes on there website and they are ready to make good commissions on the basis of traffic they attract and clicks or sales or leads whatever occurs. So in case of server companies who provide free space of 7 to 10 gb Use this service to attract and generate traffic to their website. Not every body clicks the ad but for instance, They attract around 100000 visitors per month through "Free Online Storage" and about 10 percent of them clicks those ads they can make as high as 10000 x Earning per click = Their Commission it may be that google adsense pay them around 0.30 to 1 USD per click so they can earn anywhere between 3000 to 10000 USD

there you get it how it works

Hope that helps…