Vertical antenna

Vertical antennas, often simply known to amateurs as "verticals," are antennas in which the driven element is vertical. Most common verticals are simply a piece of wire or aluminum tubing mounted vertically, but others, such as those designed for mobile use, are significantly more complex.

Efficiency
Refer to KE4UYP's Vertical Antenna efficiency article for more discussion.

Loaded Verticals
Antenna loading is the practice of shortening antennas to less than the length that resonance would normally require, then adding reactive elements to bring them back to resonance. They are very useful when the space a full-size antenna would require is not available. All verticals designed for mobile use must use some type of loading.

See antenna loading for a detailed discussion.