Business cycle and aggregate demand and inflation

2.1 Refer to chart 1 below which shows Australia's 'output gap' since 1980 and answer the following;

Explain what does the term 'Output gap' means?

What do these economic fluctuations mean, that is where the line graph is above and below zero?

How do positive and negative 'output gaps' impact on country's rate of unemployment and inflation levels?

Chart 1