The World Health Organisation (WHO) 6th Edition reference values classify sperm motility into three categories: progressive motility (sperm moving forward efficiently), non-progressive motility (movement without forward progress), and immotile sperm. For a normal sample, WHO criteria require total motility of at least 40% and progressive motility of at least 32%. These classifications are used by all clinical sperm analysis equipment and CASA systems, and form the basis of fertility assessment in andrology labs in the UK and internationally.