Sometimes it's surprisingly difficult to tell the difference between a digitally altered photo and an authentic one. Some are stitched together so perfectly they fool even the experts.
We've rounded up 13 of them, so next time you see any of these photos floating around, you can help spread the word.
Some of these you may not have seen before. Others are classics that resurface every now and again and simply will not die no matter how hard people try to debunk them.
1. This is not a photo from Hurricane Sandy.
This photo was shared widely during Hurricane Sandy in 2012. Even some news sources are guilty of spreading it around. But as many sources have pointed out, it's actually just a shot of the Statue of Liberty with a giant supercell caught by storm chaser Mike Hollingshead Photoshopped in.
2. People don't really watch the sunset on screens in China.
This photo inspired sensational headlines like "Beijing Watches Fake Sunrise on Video Screen Amid Smog Emergency" and "Finally, a Better Way to Watch the Sunrise in Smog-Filled Beijing." The smog in China is a serious health concern and environmental problem, but the screen in question is actually a digital billboard and the sunset is part of tourism advertisement.
3. Sharks swimming through flood waters are not a thing.
According to the Bangor Daily News, the picture was originally posted on Facebook by a man in Texas as a joke. But things got out of hand. What's more, this is not the only hoax shark-flood photo out there.
4. And this is not a Megalodon shark swimming alongside Nazi U-boats.
Sadly, you can thank the Discovery Channel for this one — specifically, its Shark Week TV special that seems to have less science and more hype every year, according to marine biologists who have spoken out against the show.
The photo showed up in a Megalodon "documentary" that aired during Shark Week. George Monbiot points out a lot of problems: For one, Nazi photos weren't typically watermarked with swastikas.
5. Don't even get us started on "northern lights" photos. Well OK, maybe just one.
It's absolutely beautiful, right? Too bad it's not real. The image was created using a photo of a mountain range overlaid on a Hubble image of deep space. There are lots of fake northern lights photos out there.
6. The "missing link" fossil was actually a complete hoax.
In 1912, scientists discovered fragments of a jaw and skull that proved man had really evolved from apes. It was deemed "the missing link" between us and our distant ancestors... except it wasn't.
Modern fluorine dating revealed the human skull was about 50,000 years old. The jaw was only a "few decades old," according to Hoaxes.org, and belonged to an orangutan. It had been stained to make it appear older. Experts concluded the skull and jaw were planted at the excavation site.
7. This is not a black lion.
8. Nope, these aren't purple trees.
The photo seems to have originated on Pinterest with a caption that read "The Fairy Pools, Isle of Skye, Scotland." This is actually a shot of the Shotover River in New Zealand, where the trees are green and the water is a more normal shade of blue.
9. The supermoon was too beautiful to be true.
A supermoon is a phenomenon that happens every year when the moon becomes full during its closest approach to Earth. There are tons of photos of supermoons that look too incredible to be real. Sometimes it's hard to tell the real ones from the fakes. The National Parks News couldn't even tell this one was a fake:
The truth? It's actually a landscape shot with the moon added in. Here's the image without the supermoon.
10. This is not how bright India is from space.
This is one of those photos that's gets passed around a lot. Often it's labeled as India from space on the night of Diwali, the festival of lights. It's actually a composite image of how lights have changed in India from 1992 to 2003.
11. This is not a shooting star. Seriously, have you seen a shooting star?
Every once in a while, these kinds of photos will get passed around as if they were shooting stars. It's actually a long-exposure photo of a space shuttle launch, as Twitter user PicPedant points out. And it's actually from a NASA Astronomy Photo of the Day post that includes the full description.
Here's one of SpaceX's own long-exposure launch photos for comparison.
12. This is not a solar eclipse as seen from the International Space Station.
This is actually a tricky one, because it's made using pieces of real space photos. The most telling part is you wouldn't be able to see any of those stars in the background during a real eclipse, according to Discover.
13. We wish this were a real long-exposure photo of lightning. It's definitely not.
It was actually created by artist Darius Twin, who creates "light painting" images.
Bonus: Every UFO photo ever created by Billy Meier.
But trust us, the Apollo moon landing photos are 100% real.