The gland between your two eyebrows is called the Pineal gland, and for a long time, it was considered the most mysterious part of the body. Mainly because at the time, no one knew its function. It's nicknamed "the third eye". Many philosophers speculated about the gland's special qualities. Descartes called it the "principal seat of the soul".
Close your eyes and focus on the space just in the middle of your two eyebrows. This is hard to believe until you actually try, but you'll find it easier to focus your attention on this region, compared to other parts of the body. Osho describes this gland as "magnetic" because of the way it absorbs your attention. So focussing on it is a great way to concentrate, and immerse yourself in the present moment
Source: The Book of Secrets, 112 Meditations - Osho