Hit-to-kill (HTK) is a military weapons design technique, which is sometimes equated with kinetic kill, of which it is a subset. HTK is a scaled-up version of the way a bullet from a rifle does damage: transferring mechanical energy to the target, rather than using explosive force. Explosives, however, are also kinetic-kill, but disabling with electronic warfare can be a non-kinetic-kill.
Perhaps the most common use of HTK is in ballistic missile defense, and in some cases of counter-rocket, artillery and mortar systems. Those applications differ from ordinary rifle bullets, as they exploit the combined energy of a rapidly moving target warhead with a rapidly moving interceptor. The combined mechanical energy of an interceptor crashing against an incoming ballistic missile is far greater than any non-nuclear explosives would provide.
HTK is also used, with precision-guided munitions, against ground targets in populated areas, and other cases where collateral damage is to be devoided. A good-sized concrete warhead, hitting an artillery piece at supersonic speed, will ruin the target's day, and the rest of its (nonexistent) days.
It is an appropriate technique for intercepting warheads in space, because the shock waves of conventional explosives do not propagate in a vacuum.