The
\hline
command will draw a horizontal line the width of the table.
It's most commonly used to draw a line at the top, bottom, and between
the rows of the table.
Two successive \hline
commands leave a space between the
lines; this space does not contain the vertical lines
specified by |
characters in the col
argument of the
\begin{tabular}{col}
command.
To place a line at the bottom of a table, the \hline
command
must follow a \\
(line break) command
after the last table entry. This final line break command should be
present only in this circumstance.