[pdftex] color

[Kevin E. Cahill]

How does one get color in the text and
equations of a latex document?
When I try \textcolor{red}{PIPE}, 
pdflatex (and latex) says 

! Undefined control sequence. 
\textcolor
          {red}{PIPE}

-- 
Kevin Cahill                         Phone:                  505 277 5318
Department of Physics and Astronomy  Fax:                    505 277 1520
University of New Mexico             Web page: kevin.phys.unm.edu/~kevin/
Albuquerque, NM 87131-1156           E-mail:               cahill at unm.edu