The app snapchat has the special function that received or even sent pictures will be deleted within a very short time from your smartphone. This can be quite a shame if you have a friend who sends you a sweet or cute image and you want to keep this as a reminder. To ensure that you can save images from snapchat, you have to apply the following little trick.
Use the screenshot function of your smartphone. The screenshot will save the currently shown snapchat content into an image file, thus also the snapchat image.
However your contact from whom you received the image is informed by Snapchat through a message that the image has been saved with a screenshot. You know now how to save an image in snapchat, even if it is deleted after a short time from the app.