A mousetrap is a mousetrap. Mousetrapping is therefore a trap into which the visitor of a website falls and from which he can no longer get out.
In a mousetrap website, all the functions that can be used to leave the website are inactive; the visitor can no longer leave the website and surf to another Internet address. When trying to close the browser window to go to another URL, mousetrapping automatically opens a new browser window with the new URL, but the browser stays with the mousetrap URL.
There are different flavors of mousetrapping. Some mousetraps open a limited number of browser windows, so that persistent visitors can leave the trap. Others open an unlimited number. The visitor then has no choice but to press "Ctrl+Alt+Del" or restart the computer.