Vajrayana (Diamond Vehicle) is a fast path to enlightenment, achieved through use of tantra techniques. It is a complex spiritual system. It is based on the teachings of Buddha, but were extended by the mahayana path of love and by a lot of techniques from Indian yoga. Monks developed in the Middle Ages a comprehensive system of teaching that is imparted in a long-term training and tailored to the needs of people in Tibet. Advanced monks and nuns is recommended a three-year meditation as a yogi in seclusion.
A major problem is the adaptation of Tibetan Buddhism in the modern world and in particular to the needs and possibilities of people in the west. The Dalai Lama tries to create a modern Buddhism based on the equalty of men and women, democracy and less strict sexual rules. He permits masturbation for monks and accepts homosexuality (Luise Rinser, Compassion as a way to peace, 1995, page 80).
In principle the Tibetan Buddhism is very simple. It consists of the Kundalini Yoga, the meditation in silence and the path of all-embracing love. With Kundalini Yoga the kundalini energy (enlightenment energy, happiness energy) is awakened through yoga postures, breathing exercises, mantras and visualizations. The center of tibetian meditation is the deity yoga. Through the visualization of various deities the energy channels are cleaned, the chakras are activated and the enlightenment consciousness is created. By special methods the ego will be dissolved and the Yogi enters into the bliss of nirvana.
A key element of Tibetan Buddhism is the work with an enlightened Master. The enlightened Master transmits enlightenment energy to his students after an initiation. The great advantage of Tibetan Buddhism is that there are many enlightened Masters who regularly travel to their western groups. Also possesses the Tibetan Buddhism with the Dalai Lama an inspiring leader who is often seen by Western television. The Dalai Lama represents the cooperation of all religions and initiates also people who do not belong to the Tibetan Buddhism.
In Tibetan Buddhism there are five major lineages: the Gelugpa (emphasis on compassion and spiritual training), the Kagyupa (emphasis on meditation), the Sakya (emphasis on the wisdom), the Bonpo (traditional shamanism) and the Nyingma (the non-dogmatic way). The Nyingma emphasize the spiritual development from the inside. They teach the individual path. Nyingma yogis may also live in a relationship.
The founder of Tibetan Buddhism is Padmasambhava. He lived some 1200 years ago as a yogi in India and was invited by the Tibetian King Trisong Detsen. He knew a lot of spiritual methods and taught a diverse mix of yoga techniques (Hatha Yoga, Karma Yoga, Mantra Yoga, Tantra Yoga and Guru Yoga). He said, "Practise so that you feel comfortable. Whenever there is a doubt on your way, then pray to the enlightened Masters, think for yourself and follow the voice of your inner wisdom. This is the voice of the enlightened Masters. If you do this, you will win on your spiritual path."
---> For advanced see also Wikipedia: Tantra techniques (Vajrayana) (Deity Yoga, Guru Yoga, Clear Light Yoga, Death Yoga, Tantric Sādhana)