Drag to move along the line. Zoom with the buttons, the mouse wheel, a pinch, or the + and − keys. Click the line to pick a year; the arrow keys move it. Click an event to read about it, or a number on the line to zoom in on its events. A solid bar shows how long something lasted; a pale band shows the years in which something happened when historians or scientists are not sure of the exact date. Zoom out past Millennia to Mega-annum (millions of years) and Giga-annum (billions of years) for the story of Earth.
