How to draw table borders in LaTeX

Take an example of two column table.

\begin{tabular}{cc}
Book & 30 \\
Pen & 5
\end{tabular}

If you add a vertical bar | to cc;

\begin{tabular}{c|c}
Book & 30 \\
Pen & 5
\end{tabular}

\begin{tabular}{|c|c}
Book & 30 \\
Pen & 5
\end{tabular}

\begin{tabular}{|c|c|}
Book & 30 \\
Pen & 5
\end{tabular}

LaTex draws the borders of table or cells.

Horizontal line

The command \hline draws a horizontal line in a table.

\begin{tabular}{|c|c|}
\hline
Book & 30 \\
Pen & 5
\end{tabular}

\begin{tabular}{|c|c|}
\hline
Book & 30 \\
\hline
Pen & 5
\end{tabular}

\begin{tabular}{|c|c|}
\hline
Book & 30 \\
\hline
Pen & 5 \\
\hline
\end{tabular}

Let's see the last table in the above example. The row Pen & 5 has \\ unlike other two tables. If removing \\, LaTeX throws an error.