Stammering facts and the stigma surrounding it. Stammering is when someone repeats, prolongs, or gets stuck when trying to say sounds or words (stamma.org)

Stammering is characterized by signs of visible tension as the person makes effort to speak. This is however different from normal disfluencies that all speakers experience in that they can last longer, happen more frequently, and are produced with more effort and exertion

Although the exact cause of stammering is unknown, research suggests that it is neurological. This implies that persons who stammer have a different way of producing speech in their brain.