High blood pressure is called the silent killer because often there are no symptoms.
Blood flowing with too much force puts pressure on arteries stretching them and causing small tears. Tears are repaired with scar tissue which traps fat/cholesterol. The plague leads to hard, weak arteries.
High blood pressure causes strokes, heart attacks, kidney failure , and heart failure. The best numbers are less than 120 on top and less than 80 on the bottom.
Source: University Hospitals Elyria Medical Center 2018