Vipassana means clear seeing, and is often translated as insight.
In the West, we hear much about vipassana meditation, but the problem I have with the phrase is that there is really no such thing! The Pali Canon does not mention it, and the reason is that vipassana or insight in the Pali Canon is a quality that you develop from practising the correct meditation. It is not a type of meditation, but something that correct meditation leads to. (The Pali Canon Suttas are the best records we have of what the Buddha actually said about meditation; see my article Buddhist Scriptures on this site).
The various styles of vipassana meditation that I have learnt, or read about, or been taught on retreats, often seem to reflect this imprecision. I find they can be vague; there seems to me to be something missing. The meditation instructions are usually to be aware or conscious of what you sense, whether within or without, and work with it in some way - either just note it and move on, hold it in overall awareness, focus on it, or do nothing at all with it but just let your awareness be of the never ending stream of mental events and sensations, like watching a movie on a white unchanging screen.
I don't see anything wrong with these styles of meditating - in fact, I have embraced them and found them valuable. But to me, it is not enough. I need some direction; I need an anchor, even if only a temporary one, in the midst of all my random thoughts and sensations; I need to know what to do. Of course, doing has bad press among meditators - being is what it is all about, and doing is what all those suffering non-meditators are locked into!
This leads me on to the Pali word jhana (Sanskrit dhyana, also zen), usually translated as concentration. I see three different uses of the word jhana in the Buddhist scriptures:
1) The first meaning is close to the word meditation. It is the activity that the Buddha tells his disciples to do; he does not say go do vipassana, but go do jhana, in the sense of find a quiet spot, sit down, be still and focus inside - much like we use the word 'meditation'.
2) The second meaning is somewhere between 'concentration' and 'absorption'. The Buddha talks of levels of jhana in this sense, states of concentration where one is absorbed inwards.
3) The third sense of jhana is the meanings and interpretations that the Buddhist commentaries have added to it. I find these not only unhelpful, but actually contradictory to what the Pali Canon says about jhana. The Commentaries have built jhana up into a high-octane state that is very hard to get to, with special signs which the Pali Canon do not even mention, and that are accessible to only one in billions! (See Brassington for a summary of the differences between the Sutta and Commentary jhanas, and see Sona for a specific example of how a simile for an experience - 'like the moon' - in the suttas gets garbled in the Commentaries to a 'sign' that you actually have to see in yourself!).
Even worse, the Commentaries have made jhana daunting, frightening even, warning meditators that it is a dangerous place to go to, you can get lost in them and forget your true purpose! Many vipassana teachers in the West today warn people not to get lost in jhana.
I don't find any of this in the Pali Canon Suttas; in fact, quite the opposite, jhana is what you do, and jhana is what you go for, on the way developing vipassana and all the other fine qualities of choiceless awareness (this is Krishnamurti's phrase, but often used by Buddhist teachers).
And this is the key point: jhana is not just mindless concentration, bringing the errant mind again and again back to the point of concentration, like a grim repetitious treadmill task; but a mindful concentration, needing some effort of course, but also skill and awareness, which is intensely enjoyable.
The Buddha's formula, mentioned many times in the Pali Canon, is (with my comments in brackets) to: ... remain focused (keep track, concentrate) on the body in and of itself (or whatever the object of concentration is) -- ardent (making effort), alert (aware of what is actually happening), and mindful (keeping the task in mind) -- putting aside greed and distress with reference to the world (focusing on the concentration point in and of itself, without relating it to its context or storyline elsewhere).
I think of the process as a soft-focus - rather like a torch or flashlight beam, which has a strong central beam and a penumbra; when you shine the torch or flashlight on a wall, you see a bright central circle, and then a dimmer circle of light (the penumbra) around the brighter central circle.
When I am aware of an experience - outer, bodily, mental - I try to observe it this way: focus on it, give myself to it; but allow a little focus to be around it, and not directly on it. This peripheral focus allows me in fact to be alert and mindful, in the Buddha's formula above; it also allows me to be open to other possibilities, to follow any metamorphosis that the object of my awareness might make.
In my analogy, attention is the bright central beam which highlights the object of focus, and awareness is the penumbra around it. Most people think of concentration as just attention - forcing all your mental energies in one tight bright beam which is just focused on the object. But this is both very hard to do, and unstable - if you lose the light on the object, it is difficult to pick it up again if there is no penumbra (rather like a searchlight trying to find a plane once it has lost it). The penumbra - awareness of what is going on around the object of concentration - is essential for clear strong concentration.
So to revert to the English terms, concentration both needs insight to develop, and produces insight as a result. Likewise, insight both needs concentration to develop, and produces concentration as a result. In many ways, they are two sides of the same coin. When I am sitting on the meditation cushion and all is going well, then I see them in this way. But when I am swamped by my thoughts and feelings, and wondering what even the point of meditation is, then concentration is what I can actually do. Insight would be nice, but I cannot do insight; but I can do concentration, and this is why I believe the Buddha talked about both doing jhana and achieving jhana as the entry point to any worthwhile realisation.