Sexting is where someone shares an intimate image of themselves with someone else. It can also mean that that person has then shared that image again - online, or via mobile phone. The image can be sent by text, IM, social networks, apps like Snapchat or Whatsapp, etc. Once an image is posted, or sent, you lose control of where it might end up and who might see it.
You can find out more about how to deal with sexting here on our E-Safety page. If you're suffering the consequences of sexting or sharing images, click here for the Safer Internet Centre's guide on how to handle it.