I came across the idea of "prompts" on GUIs when I asked this question on UXExchange.com. Two people answered that "Share This" buttons prompt readers to share.
I have never used a "Share This" button or anything of that sort. Whenever I find something interesting online, because of the highly ergonomic setup of my computer, I always had the impression that sharing content on the web would always be more convenient if I do it manually than through an automated process, which could even compromise my social networking accounts. I haven't tested this so I don't have the numbers, but it's logical that "Share This" buttons can prompt people to share information, whether they are going to use the sharing service or not.
Recently, I have notable "prompting experiences" on mobile operating systems. On the iPhone, because of the limited hardware buttons, opening menus are done through the GUI. I appreciated this when I started being an Android user. On Android; going back to the previous screen, opening menus, and searching are all done with the use of hardware buttons. How are you going to know if and how those buttons are going to work on a certain screen? You have to test. There's nothing to prompt you.
Prompting and the lack of it largely influence the world. They're the advertisements of activities.
Thoughts on People and Technologies that Extend Them