In order to emphasize text the command \emph can be used which usually displays the text in an italics font:

This is some text with \emph{emphasized words}.

The command \sout of the package ulem strikes through a text:

\sout{This text is striked through}

The package ulem redefines the command \emph. When you do not want to have this behavior you can use the package ulem with the option normalem:

\usepackage[normalem]{ulem}

In order to typeset text in bold, use \textbf:

\textbf{This text is typeset in bold.}