Tantra techniques are very ancient and some form is found in many ancient cultures. The Sanskrit word tantra implies continuation, weaving together, but there is no real single definition. Tantra includes many sets of techniques, usually action-oriented, to weave together mind and body.
We have a lot of books on Buddhism on our shelves. I took this one down to read since I'm looking for an appropriate one to give to a friend. I'm not sure this is best one. It's great someone who really wants to dive into a practice but I'm looking for a more daily practice of releasing from attachment to outcomes. Letting go of expectations. This is a good book, but probably not the one for her.