The practice of Buddhism entails consistent meditation and mindfulness for the purpose of reducing one's poisons or delusions and arriving at a clear state of mind - the Enlightened Mind of the Buddha. All Buddhists share this common goal: to bring an end to suffering by taming the mind. Since the human condition contains many different forms of suffering, the Buddha taught many paths to liberation, which are now practiced throughout the world.
Buddhism was brought to Tibet by Padmasambhava in the 8th Century, and has flourished there ever since, transmitted from Gurus to disciples in an unbroken lineage. The Tibetan practices share a distinctive motivation: they are undertaken to end not only one's own suffering, but also the suffering of all other beings, to each of whom we owe a karmic debt.
The understanding is that since we are all linked to one another, one person's liberation is incomplete until all other beings have been liberated. So with the help and guidance of the Guru, Tibetan Buddhist practitioners work to develop the pure perception which arises out of meditation. That clarity is then used to awaken and increase their compassion for others until it equals the unconditioned compassion of the Buddha.