Every square is sixty seconds of the front page — your name, your line, your link, nothing else on the screen. Pick one. Red squares are gone for good. 0 sold on this day so far.
Sixty seconds. The whole screen, nothing else on it. Shown in your local time above.
Minutes are priced by when tech X is actually awake. 14:00–18:00 UTC is the overlap between the US morning and the European afternoon, so it costs the most. 03:00 UTC is the cheapest minute of the day, because nobody is looking. The curve moves as the real traffic data comes in.
Every minute also has its own page with the time in 24 cities and everything that has aired in it — browse all 1,440.