Adjustments can take a variety of forms from very gentle to more firm. It is my opinion that the firmer treatments work faster. Not every patient can tolerate a firm treatment and this should be communicated to your Chiropractor. Most Chiropractors have studied more than one technique.
In my office we use massagers, and an arthostim unit to assist in the adjustment. More firm treatments are perfomed by hand.
Chiropractic is most popular in the treatment of lower back and neck pain. Treatment is available for the entire spine, extremities and such conditions as fibromyalgia.