All of these cryptic abbreviations represent organizations or "governing bodies" in the sport of gymnastics.
IOC - International Olympic Committee. President is Juan Antonio Samaranch. Headquarters are in Switzerland. Organizes the Olympics.
FIG - Federation International de Gymnastique (International Federation of Gymnastics). President is Yuri Titov. Headquarters are in Moutier, Switzerland. International governing body for the sport of gymnastics.
USAG/USGF - "USA Gymnastics" (operating name) or "US Gymnastics Federation" (legal entity). President is Kathy Scanlan; Chair of the Board of Sandy Knapp. Headquarters are in Indianapolis, IN. National governing body (NGB) for gymnastics in the USA. USAG is a member of both the USOC and the FIG.
NCAA - National Collegiate Athletics Association. President is Cedric Dempsey. Headquarters are in Kansas City, MO. Governing organization for collegiate sport in the USA.
AAU - Amateur Athletic Union. Headquarters are in Indianapolis, IN. Former national governing body for the sport of gymnastics in the USA. Presents the Sullivan Award each year to the beat amateur athlete in the nation.
USAIGC - US Association of Independent Gymnastics Clubs.
CGA - Collegiate Gymnastics Association.
Usually you can just call Ticketmaster for that city and they will have information. If in doubt, you can e-mail USA Gymnastics at (317-237-5050).
There is another sport called "acrogymnastics" or "sports acrobatics" in which gymnasts do compete with each other on the mat. Divisions are women's pair, women's trio, men's pair, men's four, and mixed pairs (one man and one woman). Acrogymnastics in the US is governed by the US Sports Acrobatics Federation. There are world championships held for sports acrobatics, but it is not yet an Olympic sport. It's quite popular, however, and is hoping to be a demonstration sport soon. Sports acro also includes men's and women's tumbling.
Rhythmic gymnastics is a sport that demands a high skill level in manipulating and controlling various apparatus while performing a routine on the floor mat. Gymnasts (only women participate in RSG) are not allowed to flip or perform acrobatic elements but rather concentrate on expressing their choreography, demonstrating mastery of the apparatus and performing leaps, spins, rolls, and other elements. There are five apparatus (hoop, clubs, ribbon, rope, and ball) but only four are competed each year. Gymnasts either perform alone or in groups or five. The group event will be added to the Olympics for the first time in 1996. Sometimes artistic gymnasts will turn to rhythmic gymnastics in favor of the lower rate of injury in the rhythmic version of the sport.
To enroll in gymnastics classes, check your yellow pages for gymnastics schools. Good questions to ask the gym are if their instructors are USGF safety-certified, what type of insurance coverage they have, and what programs they offer (competitive, recreational, etc.). Speak to parents at the gym for references.
Yes, most gymnasts do wear underwear, if you were wondering. Generally, in practice, girls wear tank leos and biker shorts. Men will wear shorts and a t-shirt (or whatever is handy). In competition, the women wear long-sleeved leotards, and men wear a jersey that resembles a tank-top leotard ("comp top"), with either shorts or competition pants, depending on the event they are competing. Some gymnasts will wear special shoes; if swinging bars or competing on rings, they will wear "grips" on their hands to help the secure their grip of the bar or ring. On parallel bars, men may wear tubes of fabric on their upper arms to prevent from ripping off the skin (which happens when they catch a double or other flighty skill).
The chalk that gymnasts rub on their hands and sometimes feet is magnesium carbonate. It absorbs any sweat on the hands and/or feet and enables the gymnast to improve their grasp of the apparatus.