% http://www.texample.net/tikz/examples/

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}

\begin{document}
 \tikz \fill[orange] (1ex,1ex)circle (1ex); 

\begin{tikzpicture}[domain=-2:2]
 \draw[step=1.0cm,very thin,lightgray] (-2.0,0.0) grid (2.0,4.0);
 \draw[->,thick] (-2.5,0) -- (2.5,0) node[right] {$x$};
 \draw[->,thick] (0,-0.5) -- (0,4.5) node[above] {$y$};
 \foreach \x in {-2,-1,0,1,2}
   \draw (\x,-.1) -- (\x,.1) node[below=5pt]
   {$\scriptstyle\x$};
   \foreach \y in {0,...,4}
     \draw (-.1,\y) -- (.1,\y) node[left=5pt]
   {$\scriptstyle\y$};
 \draw[red,thick] plot[smooth] (\x,{\x*\x});
 \end{tikzpicture}
\end{document}