Clogging can take place whenever a suspension, made up of discrete objects in a fluid, flows through a confined space. The constriction may be microscopic, like the tiny pores of a filter, or macroscopic, like the narrow road that produced this traffic jam in Kuala Lumpur, Malaysia. To learn about how various clogs can happen and how to mitigate them, turn to the article by Brian Dincau, Emilie Dressaire, and Alban Sauret on page 24 . (Photograph by Alexandre Roussel/Alamy Stock Photo.)