\usepackage{} -- graphicx vs. graphics vs. psfig/epsfig

Using \usepackage{graphicx} is preferable to \usepackage{graphics} because although "both packages have the same capabilities, ... the resulting syntax may be more cumbersome [with the graphics package]."  TUGboat, Volume 17 (1996), No. 1, "Tutorials" (p. 43) -- PDF,

With \usepackage{graphicx}, "you can incorporate graphics in pdf, jpg, png or tif (with one f) formats. If you don't specify the file extension, it will look for and use whichever one is available."  However you may need \usepackage{graphics} if you have .eps graphics.

% \usepackage{psfig} and \usepackage{epsfig} are obsolete. (Link here.)
% \usepackage{epsf} % Obsolete, low-level typesetting of Encapsulated PostScript (EPS) files.