What is mindfulness?
In the quote above, Jon Kabat-Zinn gives us a really thorough description. And, in trying to live into it, a challenge to us to opt in to paying attention to the detail and depth of our lives, as we are living them, and - crucially - each time we are aware of our inattention or autopilot, to reconnect to what is really in this moment: this breath, this ache, this urge, this thought.
Mindfulness challenges us to not be blinded by our habits, preconceptions and automatic reactions, as we approach the moments of our life.
What is mindfulness meditation?
Meditation is a way of saying 'technique'. So mindfulness meditations (formal and informal) are simply techniques which enhance our ability to pay attention to the present moment - to be mindful - in daily life.
How do I know it will work for me?
You don't. But you can try it and see... be a scientist of your own experience. Observe.
There is a lot of writing about mindfulness. The neuroscience research base is growing, and as a result there is inspiring evidence demonstrating the benefits of mindfulness meditation available online. In addition to what you will find with some web research, there are many excellent authors in your local library.
Much of this is useful and may well support your practice, but none of this is mindfulness. As you live with the impacts of the techniques you employ, you will be well placed to evaluate how your mindfulness practice affects your life.