Meditation techniques are methods of not thinking (or occasionally highly directed thinking).
Meditation has as an initial goal the silencing of the internal verbal dialog which most (but not all) people expeirence as a constant flow of conversation between different aspects of their selves. "Slipping into the gap between thoughts" gives an experience of the self not as a "speaker" - as a voice - but as a "perciever" - a listener.
This shift in identity, from the fundamentally active-but-chaotic self as a stream of words, to a passive-and-silent mode opens up many, many new forms of perception and gives a fundamental break from the chaos of the mind.
Even a few seconds of this silence can change the way the universe is understood. Repeated experiences can cause a person to identify with the silence inside, rather than with the rampaging inner voices.
Classical approaches to meditation include:
Concentration on the breath, having the awareness following it in and out.
Repetition of a mantra, such as "hari tat sat om", the Hare Krishna mantra or "Aum Naman Shivaya." When the mind strays from the mantra, and you are aware of your thoughts, return to the mantra.
Visual focus on an object such as a candle, or a picture of a god.
Reading a mystical text, such as "The Book Of The Law" and holding each verse in mind as an object of meditation.
As a rough guide, half an hour of practice morning-and-evening for about five years is usually enough to allow entry to the internal silence on a regular, at-will basis. Profound effects can be experience much more quickly by some people, but in general the process is slow, although rewarding at every step.