Egypt attack: Fake Sinai photos on social media
How do you know if the photographs and video footage that you see on social media after an attack are real?
In the absence of concrete facts, many people - and news organisations - turn to social media for information.
In its immediate aftermath, news site Al-Araby shared a dramatic image of crowds outside a smoking building.
The headline read: "Sinai: 200 people killed and wounded in the bombing of a mosque".
The ambulance shown is indeed Egyptian. However, this image does not show the 24 November attack in Sinai.
How do we know?
By conducting a reverse image search, we can see that the photo was actually taken by a photographer working for the news agency AFP in 2015.
It shows the aftermath of a bomb attack in another Egyptian town which killed eight people.
There are several ways of conducting a reverse image search.
If you're using Google Chrome, you can right click on an image and select "search for image".
If you're using a different browser, you can save the image and then re-upload it to a reverse image search tool.
You'll then see the other places on the internet where it appears.
Other social media users shared a video supposedly taken "during the bombing of al-Rawda Mosque" in Sinai.
But this video was in fact first uploaded by Twitter user Mohammad Boland in early 2015, during an attack on a Shiite mosque in eastern Saudi Arabia.
The original version of the distressing video, which was shown on American news network CNN, is much higher quality.
Video quality can be degraded when it is downloaded and re-uploaded - which makes it harder to find the original when you carry out a reverse image search.
The wrong mosque
Another way of spotting a fake photo is to check the surroundings.
Several users had shared a photo that showed a minaret collapsing during an explosion. But the minaret was not from the mosque in Sinai.
It was taken in Mosul in 2014.
If you come across that photo, compare it to the minaret from the mosque in Sinai, below. They clearly do not match.
There are plenty of genuine images of the devastating attack in Sinai and its aftermath. But there are fake photos in circulation - and by right clicking and carrying out your own reverse image search, you can check from where they really originate.