I'm Feeling Lucky is a way to search using Google, accessible on their homepage. When the button is clicked, it automatically sends the user to the top-ranked website on the search list for whatever they searched. When instant search is on, it can be accessed by hovering over the suggestions that appear as the user types.
According to Google cofounder Sergey Brin, Google loses 110 million dollars every year due to the existence of this button. Since the button sends the user to the top-ranked website on the search list for whatever they searched, Google is unable to show search ads on one percent of all of its searches.