V ipassana , which means "seeing clearly" or "insight meditation," is commonly understood as "mindfulness practice"--the task of observing activity in the mind or body on a moment-to-moment basis. It helps develop the quality of "presence" where you can learn to focus on whatever is happening in the moment without aversion or attachment. Meditators may sit for an hour or so watching their breath, physical sensations, thoughts, feelings, or sounds, with calm non-judging awareness. The Experience of Insight , by Joseph Goldstein, is a classic of vipassana meditation. Also, for background: What the Buddha Taught, by Walpola Rahula, and Living Buddhist Masters, by Jack Kornfield. Or see Access to Insight, a website with a list of retreats that is informally connected to a vipassana meditation center called the Insight Meditation Society.
All the Buddhist terms in this story are from the Pali, the ancient language spoken at the time of the Buddha (around 500 BC) in Northern India and still spoken and written in some Southeast Asian monasteries. Pali is the language of Theravadin Buddhism, the kind that I practice.
Hindu and Mahayana Buddhist (including Zen) texts are in Sanskrit, which is also still spoken in India by Brahmins conducting religious ceremonies.
Although hundreds of Buddhist sects and lineages have traveled to the U.S. with Asian immigrants, Westerners who practice Buddhism generally fall into one of three main categories (with hundreds of subdivisions): Zen (from China, Japan, Korea, and some of Vietnam); Tibetan; and Theravadin (from Thailand, Burma, Sri Lanka, Vietnam, and Cambodia).