Time for action – emphasizing on a sans-serif font

We shall write our complete document using a sans-serif font. As we did not yet see how emphasizing without serifs looks, we will try that:

1. Take our "Hello world!" example and modify it this way:

   \documentclass{article}
   \renewcommand{\familydefault}{\sfdefault}
   \begin{document}
   \emph{Hello world!}
   \end{document}

2. Typeset. LaTeX will print out a warning:

   LaTeX Font Warning: Font shape `OT1/cmss/m/it' in size <10> not available

   (Font) Font shape `OT1/cmss/m/sl' tried instead on input line 4.

3. Check the output:

   

What just happened?

The macro \familydefault stands for the default font family which shall be used in the LaTeX document. For this macro, we specified the value \sfdefault, which means the default sans-serif font. This means simply that sans-serif is now default, no matter which font has been chosen. As you can imagine, other possible values are \rmdefault and \ttdefault. By changing \familydefault, we don't have to write \sffamily again...