**
Asymptote
** -
A line that a graph approaches without touching.

**
Axis of Symmetry
** -
The line over which a graph can be reflected without altering the graph.

**
Hole
** -
A single point at which a function has no value.

**
Horizontal Asymptote
** -
If a graph has a horizontal asymptote of
*y* = *k*
, then part of the graph
approaches the line
*y* = *k*
without touching it --
*y*
is almost equal to
*k*
,
but
*y*
is never exactly equal to
*k*
.

**
Symmetry
** -
If a graph does not change when reflected over a line or rotated around a point,
the graph is symmetric with respect to that line or point.

**
Vertical Asymptote
** -
If a graph has a vertical asymptote of
*x* = *h*
, then part of the graph
approaches the line
*x* = *h*
without touching it --
*x*
is almost equal to
*h*
,
but
*x*
is never exactly equal to
*h*
.