Delay differential equations are of sufficient importance
in modelling real-life phenomena to merit the attention of numerical analysts.
In this paper, we discuss key features of delay differential equations
(DDEs) and consider the main issues to be addressed when constructing robust
numerical codes for their solution. We provide an introduction to the existing
literature and numerical codes, and in particular we indicate the approaches
adopted by the authors. We also indicate some of the unresolved issues
in the numerical solution of DDEs.