Clickjacking is an attack that fools users into thinking they are clicking on one thing when they are actually clicking on another. Its other name, user interface (UI) redressing, better describes what is going on. Users think they are using a web page’s normal UI, but in fact there is a hidden UI in control; in other words, the UI has been redressed. When users click something they think is safe, the hidden UI performs a different action.
Clickjacking itself is not the end goal of the attack; it is simply a means of launching some other attack by making users think they are doing something safe. The actual attack can be virtually anything possible via web pages. This ranges from malicious actions, such as installing malware or stealing credentials, to more innocuous things, such as boosting click stats on unrelated sites, boosting ad revenues on sites, gaining likes on Facebook, or increasing views of YouTube videos.