The navbox (the search bar at the top of every page) is where you go to find cards in your Deck. You can also add new cards from it.
On this site there's a blue navbox in the upper right hand corner.
Every Deck has a card named *navbox.
Like any card, { {*navbox}} can be used to include the navbox anywhere, for example in layouts. The Classic Layout does just that.
Typing characters in the navbox will trigger a box of links to open below. There are four kinds of links: