For most purposes, the features of \newcommand suffice. Nonetheless, \newcommand lacks some interesting features like the ability to make definition global or to use the \protected prefix supplied by e-TEX. This--surprisingly small--package makes possible to pass an optional argument \newcommand so that is becomes possible to use the \global and \protected prefixes. This material is subject to the LaTeX Project Public License. See http://www.ctan.org/tex-archive/help/Catalogue/licenses.lppl.html for the details of that license.