this area of forum is simply too complicated for me. i lack alot of understanding of terms (what are "gliders",
These gliders are called gliders because they don't have their own engines... they are launched with an old ICBM and then they just glide at very high speed to their target.
"mirv-why couldnt be maneuvreable till now",
A Mirv is guided towards its own target but it has no propulsion so it can't travel a long way to get to its target.
"balistic vs cruise",
Ballistic is like a bullet... it is accelerated up to flight speed and then coasts to the target... they are usually fired up into the air and then travel a curved trajectory to fall on the target. A cruise missile has its own engine and flys all the way to the target. both have guidance systems.
"scramjet-and why their are better that ramjet", and others).
A Ram Jet is a type of jet engine that is very simple. Air goes in one end of a tube and as the tube gets narrow the air is compressed which heats it up. Fuel is added and burned which generates more heat so the air exits the rear of the ramjet at high speed and high temperature... that generates thrust. Increasing the fuel supply increases the thrust.
A scramjet is a special type of ramjet where the air inside the jet engine can be burned supersonically... s c ram jet the s means supersonic and the c means combustion... so a scramjet is a supersonic combustion ramjet.
A normal jet engine would choke on supersonic air so they have special intakes to slow the air down. A scramjet could fly as fast as you want because it doesn't need to slow the air coming into it to subsonic speeds to burn fuel inside.