A ballistic missile has a ballistic trajectory that is predetermined, delivering the warhead to a predetermined target. The missile is guided just for the initial phase, while for most of the flight period it is governed by the laws of ballistics.

Like an arrow or a spear, ballistic missiles are pushed into the atmosphere by its engine, and then most part of the flight is affected only by gravity.

Most ballistic missiles have three phases to its flight: The initial powered flight period, the natural ballistic trajectory and the reentry period when the missile reenters Earth's atmosphere.

Nazi Germany's V-2 rockets are the first modern ballistic missiles that achieved sub-orbital spaceflight. Carrying conventional explosives, the V-2s struck terror and are believed to have killed at least 7250 people outside Germany, especially in Britain. Over 3000 of these rockets were fired during the World War II. Its destructive capabilities apart, V-2 significantly contributed to the huge successes of mankind in space flights. In fact, V-2s blazed a path, of countries first developing missile capabilities and then creating space flight abilities from that. India probably remains a rare exception, its missile abilities coming from its already successful space capabilities.

Ballistic missiles have established themselves as the most potent battle capability of nation, especially in case of nuclear powers who can deliver nuclear weapons. The lack of comprehensive defence against ballistic missiles makes it all the more potent. There are efforts underway in various countries to develop a comprehensive ballistic missile defence, but there is yet no report of cent percent success.
Ballistic missiles can be launched from different platforms—from mobile platforms mounted on trains and trucks, and silos; from submarines underwater; from ships on water; and aircraft.

A ballistic missile carry some form of fuel and oxygen, since they do not burn up the oxygen from the atmosphere and this also gives it the capability to fly beyond the atmosphere and reenter the atmosphere.
A significant portion of a ballistic missile is filled with solid or liquid fuel. Solid fuel can be powdered metals such as magnesium or zinc, which is mixed with solid oxygen. Liquid fuel would be a rich distillate mix of carbon and hydrogen, which combines with liquid oxygen in the engine to ignite.

At the bottom of a ballistic missile is their engine and direction control, either thrusters or fins. On top is the warhead, followed by the guidance system. Some ballistic missiles have the capability to receive signals when they are very close to targets and make minor amends to their path.

TYPES OF BALLISTIC MISSILES

Intercontinental Ballistic Missile (ICBM): Range over 5500 kilometers
Example: SS-18 and SS-24 of Russia; Minuteman and Peacekeeper of the US

Intermediate Range Ballistic Missile (IRBM): Range 3000-5500 kilometers
Example: Agni III of India

Medium Range Ballistic Missile (MRBM): Range 1000-3000 kilometers
Example: Agni II of India

Short Range Ballistic Missile (SRBM): Range less than 1000 kilometers
Example: Agni-I of India

Battlefield Range Ballistic Missile (BRBM): Range less than 200 kilometers

Tactical Ballistic missile (TBM): Range between 150 and 300 kilometers