The font selection scheme used in LaTeX2e differs a lot from that used in LaTeX 2.09. In this section, we give a brief description of the new commands. A more detailed description with examples is given in The LaTeX Companion, and the interface for class- and package-writers is described in LaTeX2e Font Selection.
\rmfamily
\sffamily
\ttfamily
\mdseries
\bfseries
\upshape
\itshape
\slshape
\scshape
These are font commands whose use is the same as the commands \rm,
\bf, etc. The difference is that each command changes just one
attribute of the font (the attribute changed is part of the name).
One result of this is that, for example, \bfseries\itshape produces
both a change of series and a change of shape, to give a bold italic
font.
\textrm{<text>}
\textsf{<text>}
\texttt{<text>}
\textmd{<text>}
\textbf{<text>}
\textup{<text>}
\textit{<text>}
\textsl{<text>}
\textsc{<text>}
\emph{<text>}
These are one-argument commands; they take as an argument the
text which is to be typeset in the particular font. They also
automatically insert italic corrections where appropriate; if you do
not like the result, you can add an italic correction with \/ or
remove it with \nocorr. The \nocorr should always be the first or
last thing within the {<text>} argument.