PFP stands for ‘picture for proof’. It is an acronym for profile picture, which is the small image that shows on social media platforms near a person’s name. Many people upload an image to represent their persona, rather than use an identifiable personal picture.
Social media sites such as Instagram, Discord, Facebook, TikTok, and LinkedIn all require that a profile picture be a square image, which has contributed to the trend of ‘square’ images on NFT marketplaces. They also allow gifs (moving images).