Walking meditation is a form of meditation in action.
In walking meditation we use the experience of walking as our focus. We become mindful of our experience while walking, and try to keep our awareness involved with the experience of walking. Actually, there are several different kinds of walking meditation. We'll just be looking at one of them in detail, although we'll touch on the others. Once you've mastered one form, you'll easily be able to pick up the others.
Obviously, there are some differences between walking meditation and sitting meditation. For one thing we keep our eyes open during walking meditation! That difference implies other changes in the way we do the practice. We are not withdrawing our attention from the outside world to the same extent that we do when we are doing the Mindfulness of Breathing or Metta Bhavana practices. We have to be aware of things outside of ourselves (objects we might trip over, other people that we might walk into) and there are many other things outside of ourselves that we will be more aware of than when we are doing sitting - especially if we sit inside. These include the wind, the sun, and the rain; and the sounds of nature and of humans and machines.
But one of the biggest differences is that it's easier, for most people, to be more intensely and more easily aware of their bodies while doing walking meditation, compared to sitting forms of practice. When your body is in motion, it is generally easier to be aware of it compared to when you are sitting still. This can make walking meditation an intense experience. You can experience your body very intensely, and you can also find intense enjoyment from this practice.
The form of walking meditation we'll be introducing here is best done outdoors. For your first attempt, you might want to find a park or open space where you will be able to walk for twenty minutes without encountering traffic.