Disclaimer: These are my thoughts and interpretations of what was taught during a 10-day Vipassana introductory course. I'll try to be accurate, but I'm doing this from memory so I apologize for any mistakes. I suggest the Vipassana Wikipedia entry as a starting point if you want a more neutral, matter of fact synopsis.
Summary: Vipassana is a nonsectarian meditation technique, focusing on results and practicality. One should be able to immediately see improvements in one's ability to deal with situations, with an aim towards liberty and eventually enlightenment (in the Buddhist sense). I personally found the living conditions a daily strain on my nerves, which greatly hindered my enjoyment of the 10-day course. I am currently skeptical of the results and am withholding judgment on its efficacy.
A) The Vipassana Course
Day 1 -- Observing respiration: Instructions on sitting are not given, with only the suggestion that one keeps one's back straight and head high. As such, people adopted various sitting positions. I switched between several, eventually keeping to a relaxed half lotus, both legs lying on the floor, with a couple cushions to prop my rump up. All meditation was performed with the eyes closed. The first day or so was spent trying to breathe normally and to observe the air flowing in and out of the nostril (or nostrils, whatever the case may be), feeling it on the edges of the nostril as well as along the inner walls. When one's attention wanders (which it inevitably and naturally will), gently pull it back to this task, without feeling disappointment or frustration. This exercise serves to a) begin the process of training one's mind to sharpen its area of focus and b) to get in the habit of pulling one's thoughts back to respiration, or whatever task was originally at hand. These random thoughts that distract one's brain are quite prolific in quantity, a response of the brain when given a task that requires minimal sensory attention. To paraphrase S. N. Goenka, it would be impossible to attempt to make a diary of all the thoughts that intrude onto one's meditation -- they are too numerous.
I thought of food, sure. Hamburgers and steaks and chicken curries. My entirely non-existent relationships with women, so very virtual in nature. Work and the people there. Curiously enough, I also found myself thinking, unbidden, of video games. Unreal, Warcraft 3, Diablo 2.
Day 2 -- Focusing on the triangle of nose: We shift the area of concern to the triangular area of the nostrils and include the skin of the upper lip, feeling the breath pass over this area. When one finds it difficult to get a sense of where this area is, or is unable to feel the air there, a couple harder breaths may be temporarily exercised to refocus. Once we get a hang of this, we shrink the area of focus to the skin between the nostrils and the upper lip, or the moustache area.
At this point, one should begin to find that one feels a sensation on this concentrated area. It can be anything, from something gross like the passing air to a subtle numbness. It can be a sharp prickle, or just feel cold or hot or sweaty. I often experienced a kind of poking or prodding, though I recall one time getting the sensation that three beetles were crawling around my nostril and cheek area. So real was the phenomenon that I had to resist reaching up to verify that it was imagined.
Day 3 -- Scanning the body, part by part: Now that we had trained this skill of focusing on searching for sensations on a part of the body, we were instructed to now sweep the entire body for sensations, passing the mind's eye from the top of the head down to the shoulders, over each arm to the fingers, down the chest and back, and down each leg individually. I found the hardest places to get a feeling for was my back and upper chest -- if I concentrate long enough I am able to feel my clothes against my skin, but it's arduous and slow going. I noticed that I would subconsciously expand my chest to press against my shirt so that I could feel it.
I also found myself scanning not my body from the inside out, but rather imagined a model of my body and looking at that from the outside, like a 3D wire-frame computer model being rotated in some cheesy sci-fi manner. I had to actively force myself to look out from the inside (or rather feel outwards), though for a long time I kept seeing my mind's eye as a kind of scanning laser.
Day 6 -- Sittings of Determination ("What is in the box?" "Pain."): Three times a day we would now have to perform sittings of determination, meaning we would meditate for one hour without moving, without re-adjusting our positions. This stipulation drastically changed the meditation from an exercise to real work, grueling, intensive work. I found myself reciting the Litany against fear:"I must not fear. Fear is the mind-killer.", as I allowed myself to be swallowed in pain three times a day.
The point of all this is thus: To break free from the bondage of desire and aversion, to lift oneself out of misery, one must accept that life is change, that good can change to bad and that bad can change to good. As such, one needs to learn to not despair when things go poorly and, equally, to not exult when things go well. This is easy enough to say, but Vipassana trains you to do it. When meditating in this manner, you strive to remain both aware and equanimous. That is, to be aware of the sensations as you pass your focus over your body, and to merely observe them, to keep telling oneself, "This sensation will pass" and to neither crave it (if pleasurable) nor to resent it (if painful). In this way, one conditions one's responses to situations in life. This is because when faced with a pleasant or unpleasant situation, the body reacts without the mind telling it to.
For example, when someone insults you or aggressively confronts you in some manner, your body automatically reacts without your mind (your conscious mind) thinking about it -- your heart rate increases, you become flush, you tense up, your brow may furrow, you might be holding your breath etc. This is because your subconscious mind recognizes this insult and reacts as it's been conditioned to when upset. Vipassana meditation seeks to break this conditioning, allowing you to see the situation for what it is, suppressing the typical emotional response from interfering with your ability to observe and assess the situation. In theory, this suppression will lead to an extinguished state where you have no (physiological) reaction at all to what happens, freeing your mind to act as it sees fit.
I know it sounds a little kooky but it does have a kind of logic to it. The rest of the days were pretty much working on these Sittings of Determination, and time became slower and slower. On the second day I found it difficult to accept that I had eight more days of meditation left, it seemed so agonizingly far away. With the Sittings, the last few minutes of the hour were nigh intolerable. There were times I just wanted to stand up and exclaim, "That's ENOUGH!" and storm out. Later I got better at ignoring the hurt (without ignoring the pain) and still I couldn't wait for the hour to end. I found having my eyes closed for so long suffocating, claustophobic, like trying to sleep when one isn't tired.
On the tenth day the Noble Silence (the vow to not talk, to avoid eye contact, to not gesture or otherwise communicate with the other practitioners) was lifted. When I broke it by saying hello to someone, I was unable to stop smiling and a wave of elation washed over me and I was bemused to find myself thus. I had not craved or missed talking to others, but when finally I did it changed everything.
Many people ask me if I had any epiphanies or if I feel any different. Epiphanies I do not recall, which the teachers warn not to expect. However, I certainly do feel different but it's too early to say what is causing that. It could be sleep deprivation, it could be that I lost 8lbs, it could be that I was mostly miserable for 10 days and am now free again to live (and eat!) as I choose. I do admit that it could also be because all that meditation really did make a difference, but I rather think it's too early to definitively say.