A Bull Market is a period of generally rising prices of a particular type of investment. There can be a Bull Market in the stock market, gold, bonds, wheat and etc.
Bull Market does not indicate a period of steady price gains that are uninterrupted by declines. Most Bull Markets are not straight up. "Two steps up and one step down" describes the typical Bull Market.
Bull Markets can last for months, years or decades.
Bull Markets are easy to identify after the fact. Of course, knowing that stocks were in a Super Bull Market (DJIA) from 1982 through 2000 is of little value to the investor. To have known before 1982 would have been of great value. An astute investor with such knowledge would have invested heavily in a diversified portfolio of stocks and profited greatly from the Bull Market.
The problem is in the word "know". One doesn't know for sure until the Bull Market is over. If we can't know, then what is the next best thing? Well, some type of forecast or prediction. That is what an investor is looking for when asking "Are we in a Bull Market?". The investor wants to know if the market will generally rise from the present point in time. An investor with a Bullish outlook will buy. An investor with a Bearish outlook will sell. An investment professional may possibly sell short.
Investors may also ask a different but related question... How will I know that a Bear Market is over? In other words... How will I identify the beginning of a Bull Market. Bull Markets begin when Bear Markets end. Bear Markets produce price declines and much anxiety. At the precise time when a severe Bear Market ends and a Bull Market begins, there is a lot of fear... sometimes PANIC. This presents an emotional issue. The best time to enter the market is often marked by uncertainty and fear. It is easy to invest when news is good. But can you invest when falling prices, bad news, fear and panic characterize the investment environment? The investor needs a signal to predict the end of the Bear Market and the beginning of a Bull Market... A signal that can bypass the fear and present an objective, fact based forecast. He is looking to buy low and sell high. That may require action to be taken contrary to natural and prevailing emotions.