You may receive an email from someone who says they are lonely and looking for a relationship. The person will be desirable and show a real interest in you. Over the space of months or even years they will be in regular contact with you and build an online relationship. They will ask you to send them photos of yourself and then relay nice comments on the way you look. Sometimes they may ask you to send naked pictures or videos performing sexual acts.
In reality, the person sending the messages is a member of a cyber crime group (scammer) and the person they claim to be does not exist. The photos of the person you think you are sending messages to will be stolen from a social media page or website.
After many messages have been sent and when the scammer is confident they have your trust, they will then tell you they are experiencing a problem and ask you to send them money. Common problems include they have an ill family member who needs treatment or they have lost the money needed to pay for the journey to come to see you. Others may ask you for money for a Visa so they can visit you in the UK. Alternatively, in more sinister cases, the scammer may try to blackmail you after you have sent the pictures stating they are going to share them with your family, friends or on social media unless you send them money.