An endothelial cell releases von Willebrand factor (VWF) by exocytosis of Weibel-Palade bodies. Their fusion to the plasma membrane triggers unfurling of the coiled VWF into the blood where it collects platelets to form the characteristic “beads on a string.” Anchor points containing αvβ3 integrins occur at intervals, and ADAMTS13 cuts the strings, reducing their prothrombotic potential. Professional illustration by Kenneth X. Probst.