Dry needling is a general term for therapeutic treatment involving multiple advances of a filament needle, which goes into a muscle producing pain and typically containing a trigger point. And no, dry needling is not a type of acupuncture; acupuncture is actually a type of dry needling.
Dry needling is one of the most progressive types of physical therapy treatment methods in the industry today. Nearly every state board allows physical therapists to practice dry needling in the evaluation, assessment, and treatment of patients with neuromusculoskeletal dysfunction or pain.
Note: This is not "breaking up scar tissue" as many people think. This is a neurological phenomenon of musculature reducing its tone.