Grounding is a particular type of coping strategy that is designed to "ground" you in or immediately connect you with the present moment. Grounding is often used as a way of coping with flashbacks or dissociation. In this way, grounding can be considered a variant of mindfulness.
Grounding techniques often use the five senses (sound, touch, smell, taste, and sight) to immediately connect people with the here and now. For example, listening to loud music, holding onto a piece of ice, or biting into a lemon are all grounding techniques that produce sensations that are difficult to ignore, thereby directly and instantaneously connecting you with the present moment.
http://ptsd.about.com/od/glossary/g/Grounding.htm