For all buddhist schools " Taking Refuge " embodies entering the buddhist path. It means that we made the decision to follow this path which answers our spiritual questioning and to practise it. We take refuge in the Three Jewels: the Buddha, the Dharma and the Sangha.
The Buddha: taking exterior refuge in the Buddha is to trust Buddha Shakyamuni who achieved enlightenment 2500 years ago. Taking interior refuge in the Buddha consists in acknowledging and trusting the Buddha nature or wisdom within all of us. It means that we commit ourselves to develop this Buddha nature until its achievment.
The Dharma: taking refuge in the Dharma is to trust Buddha's teachings as being the path that leads to spiritual development and the achievement of our wisdom nature.
The Sangha: taking refuge in the sangha is to trust the beings who, like Buddha Shakyamuni, are in the process of realizing their wisdom nature and are able to give us the instructions that will guide us on our spiritual journey. In a broader way, the Sangha is the whole community of buddhist followers. The people who wish to take refuge have to request it from a Lama.
"You have to understand that you are able to develop the positive qualities which are already within you and transform them into limitless wisdom and compassion. To make up your mind to work in this direction in the same way as the Buddhas of the past, this means taking refuge in the Buddha. To make the decision to pratise the path and the means to fulfil this goal, this is taking refuge in the Dharma. To make the decision to receive the positive influence and the instructions from others on the way, this is the refuge in the sangha. To do so for your own sake and for the sake of all human beings, this is the buddhist path of taking refuge."
Ringu Tulku Rimpoche