Keyboard shortcuts are a great way of speeding up certain operations in the web browser of choice. Ctrl-t opens a new tab, Ctr-s saves the displayed content to the local system, and Ctrl-l moves the cursor to the browser's address bar.

Sometimes however these shortcuts won't work and the core reason for this is that the website you are on hijacked it. Without going into too many technicalities: websites can override shortcuts by using JavaScript.

A basic example is Gmail where the shortcut /, which should open the on-page search in Firefox, moves the cursor to the site's search field instead.