3D Coordinate Grid

\usepackage{tikz-3dplot}
\tdplotsetmaincoords{75}{120}

\begin{tikzpicture}[tdplot_main_coords, scale=0.8]
  \draw[->, thick] (0,0,0) -- (2,0,0) node[right]{$x$};
  \draw[->, thick] (0,0,0) -- (0,2,0) node[above]{$y$};
  \draw[->, thick] (0,0,0) -- (0,0,2) node[below left]{$z$};
  \draw[blue!30, very thin] (0,0,0) -- (2,0,0) -- (2,2,0) -- (0,2,0) -- cycle;
  \draw[green!30, very thin] (0,0,0) -- (2,0,0) -- (2,0,2) -- (0,0,2) -- cycle;
\end{tikzpicture}