documentclass{minimal}

usepackage{ifthen}
newboolean{somevariable}
setboolean{somevariable}{false}

begin{document}

ifthenelse{boolean{somevariable}}{Text if somevariable is true.}{Text if somevariable is false.}

end{document}

documentclass{article}

% remove comment from the following line for the long version
%defCurrentAudience{long}



usepackage{multiaudience}
SetNewAudience{long}
begin{document}

normal text
begin{shownto}{long}
   Text for execs
end{shownto}
normal text

end{document}

newcommand{additionalInfo}[1]{#1}

additionalInfo{I am additional}

newcommand{additionalInfo}[1]{}

documentclass{article}

% switch comment to disable additional info
newcommand{additionalInfo}[1]{#1}
% newcommand{additionalInfo}[1]{}

begin{document}
I am always here

ædditionalInfo{I am additional}
end{document}

documentclass{article}
newififprintsolution
printsolutiontrue
begin{document}
Assignment.

ifprintsolution
Solution.
fi
end{document}