A Bull market is when Stock Markets increase in value over a sustained period.
You often hear people talk about a Bull Market or a Bear Market, and these are similar but opposite terms. A Bull Market is when Sock Market prices increase by around 20% or more over a sustained period.
This can happen when the economy is growing strongly. A recent Bull Market occurred after the Global Financial Crisis in the late 2000s. Low interest rates and other government stimulus caused stocks to grow continuously for an extended period.
But why is it called a Bull Market? When Bulls attack with there horns they swipe upwards. This compares to the Stock Market moving upwards in a Bull Market. You can see a Bull statues famously on Wall Street in New York, but other financial institutions also use them. They are typically seen as a symbol of good economic performance.