A clear GIF is a small, invisible file on a website that can track user information on the website it is visiting. It’s more or less a synonym to what a cookie is – cookies also track user data and are small, encrypted files.
In general practice, a GIF (Graphics Interchange Format) is densely used by people on social media, it’s a moving picture file that many people using, for example, Facebook Messenger, are familiar with.
Speaking about websites, it can be a more flexible choice than a usual JPEG or PNG format image. GIF is small in size and usually, websites do not slow down if they add GIFs to them. A clear GIF performs a web beacon function – it tracks if the user accessed particular content on a website.