As someone who has branded myself, as well as others I figured I'd give some of thoughts on the subject.

The "old meaning" of branding is the one that I still adhere to today. Currently I've branded myself a number of times. My brands are a cross with an S under it on my left shoulder, a Triskelion on my right shoulder, a fish (symbol of The Way) and a celtic cross on my forearms, and stigmata marks on my upper and lower wrists and side. They were all done by heating a piece of metal (normally stainless steel) until it is red-hot and applying it to the skin for a few seconds. It's not as precise as scarification by cutting (with a scalpel), but is an incredible way to permanantly mark your body. Unlike a tattoo, a brand cannot ever be removed, except for massive skin grafting.

The pain is not actually as bad is as imagined, because the extreme heat will sever and deaden the nerve endings in the area being burned, and it will go numb. Probably the most intense part of the experience is watching your flesh sizzle, and smelling the burning ozone smell of the seared flesh. If done correctly, the brand should not actually break the skin, but should leave a light brown/whitish mark where the strike (a single contact with the heated metal and the flesh) landed.

Some brands are very simple (my stigmata brands) and only require one strike. Some (the crosses) require multiple strikes with various shaped pieces of metal.

Many piercing studios will offer branding as a service. Many times it isn't talked about (sometimes for legal reasons) and may or may not be done for someone off the street, but I've had no problems finding people willing to brand. I've never gotten a brand in a studio, as I prefer to do all my own branding. For me it's a very intensly personal and spiritual experience. All my brands are spiritual in nature, and serve to mark my body with a lasting symbol of my beliefs about God. The pain and burning are all a large part of the experience, and while not always enjoyable, I wouldn't have it any other way.

Probably the worst aspect of a brand is the aftercare. To get a good scar, the brand needs to be irritated, which can take the form of scouring it with a brush in the shower, washing off the scabs, and dealing with having an open wound on your body for a few months. You have to be very careful in preventing infection when you're healing a brand.

While not for everyone, a brand is a beautiful and permanent mark on your body, and is one of my ways to set myself apart and reveal my beliefs and the truths about myself to others.