\documentclass{article}

\usepackage{amsmath}

\begin{document}

\fbox{text}
\fbox{\smash{text}} % Remove height and depth
\fbox{\smash[b]{text}} % Remove depth only
\fbox{\smash[t]{text}} % Remove height only
\fbox{text}

\fbox{skip}
\fbox{\smash{skip}} % Remove height and depth
\fbox{\smash[b]{skip}} % Remove depth only
\fbox{\smash[t]{skip}} % Remove height only
\fbox{skip}

\end{document}