The short answer to this question is that it is an approach to life in order to combat the ‘stress’ of 21st century living and improve people’s well-being.
In very basic terms it is living in the present and being aware of everything around you; experiencing whatever life throws at you with all your senses – taste, smell, hearing, sight and touch in order to stay grounded (you may choose not to be mindful while clearing up sick or changing a dirty nappy but you never know!). Key to living mindfully are the attributes of gratitude, kindness and empathy.
For a longer and more detailed exploration of mindfulness read my posts. This one may be a good place to start.
People sometimes get scared off Mindfulness when they hear about the meditative aspect to it. Yes, people who commit fairly seriously to mindfulness tend to meditate regularly in order to train their brains to be more mindful. Mindful meditation has NOTHING to do with religion and is totally secular. It is evidence-based with scientific research having proven that mindful meditation (which is very definitely NOT about clearing the thoughts from your mind but about observing and noticing them) can help with our well-being and to ‘re-wire’ the brain.
Of course there is no harm reading about different mindfulness techniques and taking on board some of the strategies without committing to meditation, however the science definitely shows that those who meditate are more likely to reap greater rewards from their mindful practices.