Meditation is an umbrella term subsuming an extensive amount of diverse practices that might include:

mindful observation, body-centered meditation, visual concentration, contemplation, affect-centered meditation, mantra meditation, and meditation with movement.

There are studies that prove the existence of a ripple effect of peace in the surrounding environment when a group meditates together. According to the unified field superstring theory in physics, waves of vibration flow from everything in the universe affecting the collective consciousness.