I can think of a service that let's people upload his/her photos on some site and this site would then ID the photos uploaded to him/her. That is sites like social networks, dating sites, and online galleries can then verify if the photo is an original by verifying a hashed version of a photo to the service.

The problem with your solution is that it requires cooperation; If I'm running a competitor of facebook, (and a dating site, in a way, is a competitor to facebook) I'm not going to want to just give them my content, you know?

You'd be better off with something like tineye or google image search; something that snarfs all the photos off the web, you know, does this regularly and timestamps where it saw the photo first. It wouldn't be 100% but would likely work better than the cooperative solution you propose, and it's something that is well within the capabilities of facebook.

Even then... yeah, I think this sort of thing is going to be pretty much impossible to completely stamp out as long as you can sell fake profiles for enough money that you can pay an actual human to create them.

Services like this do exist already, Airbnb uses one for passport verification. But would you sign up to a dating site or app that requires you to upload a copy of your passport?

Not exactly a passport. But more of an "I uploaded this image first on the internet therefore it's mine."

Or I photoshopped it enough that your filter can't see it is the same and therefore it is now mine (this is easier than you think).

Also images uploaded on Facebook aren't public by default, so tinyeye etc wouldn't have them.

Oh sorry, I misunderstood... Yes that could work, but you'd have to rely on all the big companies using it too. Getting something like Match.com to use it sounds like quite a challenge :)

What about something like "you can't be friends with these people unless you are pictured with at least some of them"? That would at least require a bunch of pictures to be taken.

Of course it's not fully thought out how it would work, maybe just for people who are new to FB? You also need some sensible image recognition algo, or you'll get a lot of chopped off head mashes. But I'm sure FB has staff for that sort of thing.

To review a language/framework that I know, I write small programs using a few of its features while learning the said language/framework. On my free time I would then browse/review those codes using a source code viewer app installed on my smart-phone.

As an aside. I just noticed that site features mostly inspiring and positive stories. The world definitely needs more news like those.

One good thing about the internet is that we can pick the kind of news that we like.

I refuse to listen to news mediums where fear and negativity are the main focus. The world is a wonderful place if we look at the right places. (Cofirmation bias anyone :)