I plan to review several applications described by delay differential equations (DDEs)
starting from familiar examples such as car following models to physiology and
industrial problems. DDEs have the reputation to be mathematically difficult but
there is a renewed interest for both old and new problems. I’ll emphasize the
need for analytical tools in order to guide our numerical simulations and identify
key physical phenomena. These ideas will be illustrated by problems in
nonlinear optics and neurobiology.