Meditation... What is it?
How do we do it?
And why?

There is no end of information available and this is simply my perspective from an exploration of 40+ years; 33 of those as a monk. So, what is it? In a word I would say 'training' – and my dictionary defines this as: "An activity leading to skilled behaviour." with a few synonyms being: "teaching, education, learning". To be clear, meditation is not passive, it is active, it is something we do. We are engaging this thing called 'me' with the intention of leading it toward some kind of (new) behaviour. The closest word to meditation in the Pāli Canon is bhāvanā = "cultivation, development, producing, in the sense of 'calling into existence'". There is also pattipada = path of practice.
There are many forms of meditation and I will first make the distinction between transformative and transcendent. The first is working with your character, your personality, your conditioning, the 'stuff' that gives rise to and constitutes your life experience, with a view to transforming it into some-thing better. You have anger issues, you drink too much, your language is dubious... etc. – the list might be quite long – and you want to 'get it sorted'. This sorting, this work, is transformative. Transcendent practices incline to the religious, the spiritual, aiming to not be bound in or dictated to by conditions. Transformation can be thought of as self-improvement while transcendence explores the actual nature of self. The two are related and practised in tandem.

How do we meditate?
This training is in relation to the mind. We can't isolate components of our being – it is a whole – but the conventional distinction of body-mind is useful. So, let's start with the body. Stop moving. Be physically still. A still body engenders a still mind (and vice versa). You can stand and meditate or you can, more classically, sit down; on a chair or on the floor. The main thing is that you are relatively comfortable, relatively relaxed. And I seriously emphasise 'relatively' in that you should not demand or expect 'perfectly' – we establish intention but do not demand... anything. Sit with your spine straight, the chest open, allow the breath and bodily energies to flow freely. Establish the intention to relax. Give attention to your shoulders, notice any tensions. Perhaps rotate them to be sure they are relatively loose, relaxed – then be still and compare the before-and-after. Likewise with your neck; study it, then rotate your head to loosen it. Again, note the difference. Sit as still as you can and give attention to other parts of your body... the heart area, the abdomen, the hands, etc. You can simply note their tone or gently massage them if there is felt tension – but don't turn this into a massage session 😊 – the aim is to simply relax, as best you can, knowing that 'perfect' is not attainable. Feel the whole body as an energy field, a sense experience. It is a mass, it has heat, it feels gravity, there are pressures and sensations. Hold these as you would hold and observe a handful of pebbles – not getting too fixed on any one. Breathe. Notice the breath. Likewise, not as a single pebble but as a flow – the breath entering the body, the diaphragm distending, your abdomen filling out drawing air into the lungs – a pause – then the exhalation – follow that with careful attention. You can use counting; one on the in-breath, two on the out, three on the in... up to ten, start again at one, the in-breath. You are opening to relaxation, to calming the body and mind with focus primarily on the breath. Those mind-bits that are not the breath are not relevant just now. You wander off, wake up to the fact that you have been wandering (at some point), and go back to the breath. Establish training in this way.
When we deliberately make our activity, both physical and mental, relatively simple the mind will naturally calm. Throwing stones into a pond will agitate the water. Just stop, be still, the water will become like polished glass, limpid, bright and clean. Sitting on the beach just watching the waves roll in and out (like the breath) is simply peaceful. Laying on your back on a clear night just looking up at the stars – ahhhh, sublime. The beauty of training with the breath is that you always have it with you – and, if you forget to bring it along... you are dead. No problems 😊. You can stop anywhere, any time, and turn your attention to the breath. Breathe in, relax... As you become more practised the association with the breath will more easily bring that calm and peaceful state of mind.
The why?
With a relatively calm mind you are more easily able to see, in any moment, your habitual reactions to a situation; you can see anger arising, you can see fear entering the mind. The habit is often just to react. If we first see, then respond, there is a bit of a gap in which we can think 'hmmm, anger – do I want to go there?'. That's the concept but the reality is not always so easy. It takes practice. Like catching a ball... as a kid you had to learn that. Maybe you missed the catch and, wham, right in the face. Anger, fear, jealousy, depression... can be like that – wham! It just overwhelms you. But, with practice, we can transform the habits of a lifetime. We can learn. Be patient.

And the transcendent?
This really warrants a separate post but here are a few thoughts. I earlier mentioned the religious and the spiritual. The word religion has its roots in the Latin word 'religio' = to gather together (unite), to connect or join. The inferred suggestion is dissolving the barriers between humans and the divine; this is primarily theological. Spirituality has a wider inference based on the sense that there is something greater than myself, some-thing beyond the material connecting with some higher power or reality. In Buddhism no such higher power or reality is defined nor is the idea of a spirit or soul. What is transcended is ignorance (avijjā = non-knowledge) – we see through our incorrect understanding of the nature of nature and we more clearly see our deluded perceptions of reality. To acknowledge that our views are subject to bias and distortion, that these views are influenced by unseen forces – upbringing, emotion, culture, etc. – is not a sign of weakness but a critical step toward authenticity, toward truth. And we are capable of seeing through our conditioning and seeing the truth. In positive terms transcendence is the arising of wisdom and freedom from suffering. Does this seem a good reason to meditate? With a clear mind you can more clearly and quietly investigate the opinions and perceptions you have about nature, especially your own nature and perhaps you see a few wonky ones. The Buddha's teaching offers many useful benchmarks against which to consider and evaluate your views and opinions.
Here are a few key principles that can be usefully considered:
Taking one of these themes and giving time to study the academic information presented online, in books, in audio talks, etc. will hopefully give you new perspectives. Bear in mind that information conflict and overload can easily happen. Keep it simple, one step at a time. Contemplate one of these principles while you sit quietly listening to the 'echo' that comes when you balance these ideas against your existing views. For example, the first one, impermanence. This applies to all things – you, your body, your mind. Will you die? Today? Do you see the naturalness of that? Are you fully at peace with that possibility? Will you lose your mind? Dementia? It is quite possible. These are just aspects of nature – like gravity, heat, cold, hunger... and we do our best to maintain our comfort but peacefully allow that 'perfectly' is not possible. When we can relax with that, truly be at peace with our current situation, our current reality, the present moment... then the mind has a stillness and tranquillity that surpasses any pleasure derived from sense distraction or material acquisition. Fully establishing a relaxed clarity and understanding moves us toward liberation (from ignorance) and the heart is naturally imbued with love and compassion.
PS. Having read through the text a few times editing I could see the repeated inclination to expand and further qualify many of the ideas here so... I have renamed it -101 with the thought that there can be a -102. Later... :)