Everything should be made as simple as possible, but not simpler.
-Albert Einstein
Trend following is an investment strategy based upon observation and assumption. The observation is of historical price movement right up until the present moment in time. There are only three possible observations: Up, down, or neither up nor down (a/k/a sideways). The assumption is that whatever the price direction has been coming into the present moment is probably the price direction going forward into the future.
The simplicity and elegance of trend following is worth a fortune in the market, in stocks, bonds, gold and options on all of the above. Whatever the price trend yesterday is probably the price trend today and tomorrow. Place your bets, you probably will win.