Poka-yoke is a quality assurance technique that aims to eliminate product defects by preventing human errors during production. It works by incorporating mechanisms that detect errors and provide warnings or corrections. Examples of poka-yoke include sensors that check weight limits in elevators and vision sensors that inspect parts on production lines. There are three main types of poka-yoke: contact methods that check physical attributes, fixed value methods that detect incorrect counts, and motion step methods that verify process steps. Implementing simple, inexpensive poka-yoke devices can significantly reduce defects and costs for companies.