Integrity is truthfulness. It is doing what you say you will do. It is a quality of being—not of doing—but the great paradox is, it is completely based on what one does.
Integrity is doing the right thing, every time. It is being upstanding and honorable. Demand integrity from yourself and seek it in the relationships you pursue.
Great friends have integrity. This means they will do exactly what they say they will do. Conditions may change. New situations may arise. Circumstances may no longer be beneficial. Nevertheless, the great friend will keep his word. He will not compromise his principles for convenience or advantage. Integrity in your friendships is critical, because it is the foundation upon which you build trust.