Steve Silberman, in an interesting post titled What Kind of Buddhist Was Steve Jobs, Really? has an especially clear and concise description of how Buddhists view meditation:
Using the mind to watch the mind, and ultimately to change how the mind works, is known in cognitive psychology as metacognition. Beneath the poetic cultural trappings of Buddhism, what intensive meditation offers to long-term practitioners is a kind of metacognitive hack of the human operating system (a metaphor that probably crossed Jobs’ mind at some point.) Sitting zazen offered Jobs a practical technique for upgrading the motherboard in his head.
The classic Buddhist image of this hack is that thoughts are like clouds passing through a spacious blue sky. All your life, you’ve been convinced that this succession of clouds comprises a stable, enduring identity — a “self.” But Buddhists believe this self this is an illusion that causes unnecessary suffering as you inevitably face change, loss, disease, old age, and death. One aim of practice is to reveal the gaps or discontinuities — the glimpses of blue sky — between the thoughts, so you’re not so taken in by the illusion, but instead learn to identify with the panoramic awareness in which the clouds arise and disappear.