Bodhi means enlightenment and Chitta means mind. Together it has the meaning of a mind that aspires to achieve enlightenment for the benefit of all sentient beings.
Bodhichitta is the foundation of Mahayana view, meditation, conduct and fruition. If we lack Bodhichitta, no matter what kind of practice we may be doing, it will not be become a Mahayana practice and hence will not become a cause of attaining the supreme enlightenment.
The great master Atisha has rightly pointed out that Bodhichitta is the differentiating factor between the Lower Vehicle and Higher or Greater Vehicle.
Bodhichitta can be of two types: relative and ultimate. The relative Bodhichitta consists of two levels: intentional and practical. After training ourselves in the relative Bodhichitta, we have to develop the ultimate Bodhichitta which has the wisdom aspect to it. The wisdom that realizes the empty nature of all phenomena is ultimate Bodhichitta. As such, Bodhichitta is not just limited to a wishful thinking or a kind heart. It is much more than that. It is aspiring in the beginning, practical in the middle and finally full of wisdom in the later stage.
Suitability: Anyone can practice. A highly suitable practice in daily life. A practice that can be integrated into every activity of life and makes positive changes in mind.