Buddhist meditation is the focusing of the mind onto a single object, or range of objects, with the intent of building awareness. Another name for meditation is mindfulness: we are simply present, aware of what is happening. When we can really notice what is going on, all the things we imagined were happening drop away until finally, what is left is the truth.
There are many different types of meditative techniques offered by the various schools and styles of Buddhism. Despite these differences, the most common anchor for the mind is the breath. The breath is completely portable; is always with us and always available to bring us back to this moment. One of the Buddha’s teachings on using
the breath is in the Anapanasati sutra. Here the Buddha tells us:
The meditator, having gone to the forest, to the shade of a tree, or to an empty building, sits down with legs folded crosswise, body held erect, and sets mindfulness to the fore. Always mindful, the meditator breathes in: mindful, the meditator breathes out. 
Formal meditation practice does involve sitting in a comfortable posture. The Yoga Sutra offers the same advice: your seat (your asana) needs to be comfortable and stable. However, this does not mean you must be in the Lotus position. If Lotus is an easy posture to maintain, without undue discomfort, for thirty minutes or longer, it may well be your ideal posture. For most Westerners, however, the pain is neither conducive to the practice nor is it good for your knees; it is better to adopt an easier posture that can be maintained for long periods. Sitting cross-legged, or even sitting in a chair, is okay if your back is straight and tall and your knees are below your hips. Sitting on a cushion, rather than right on the floor, is recommended even if your hips are very open. Regardless of which way you are sitting, or even if you are meditating while in a Yin Yoga posture, ultimately, in the words of Larry Rosenberg, “it is the mind that must sit.”
Often the student will find one teacher requests that the eyes be closed but the next teacher will tell the student that her eyes must be open. These edicts come from different traditions. In the Theravada tradition, which employs the practice of vipassana (or insight) meditation, the eyes are closed.  In the Zen and Tibetan traditions, the eyes are open or half open but cast downward. 
Each tradition has reasons for its choice. Closed eyes create less visual distraction but can induce sleepiness. Open eyes may be subjected to many distractions but it is harder to dream when the eyes are open. Since both ways are offered by various traditions, there is obviously no right or wrong way to have the eyes. Choose the option that works for you; if studying with one teacher, follow her guidance while you work with her.
What should be avoided is a constant switching between the two modes while meditating. If you believe you are allowed to open or close your eyes at any time, the danger is that thoughts will arise. You begin to debate if now would be a good time to switch modes. In our meditation such thoughts are acceptable and perhaps inevitable, but we do not wish to react to such thoughts. We simply note them and go back to our anchor, watching the breath. Meditate with your eyes open or closed, but once you have chosen an approach, stick to it.
This, of course, is just a guideline. It doesn’t mean you won’t be allowed into heaven if you close your eyes while meditating once in a while. There may in fact be times when switching is the best choice – if you find you are getting really sleepy, and suffering the full body jerks with your eyes closed, it may be better to open them. If you find your mind is just too wild with your eyes open, close them. But during a short yin pose of three or five minutes, you should endeavor to stick to one mode.
- — From Breath by Breath by Larry Rosenberg.
- — An excellent online resource through which one can learn the vipassana practice is www.vipasana.com.
- — Details of the Zen methods can be found in Philip Kapleau’s rigorous book The Three Pillars of Zen or in the gentler approach offered in Suzuki’s Zen Mind, Beginner’s Mind. Or you can go online and visit www.zenspace.org.