CrossFit (CrossFit, Inc.) is a strength and conditioning program consisting mainly of a mix of aerobic exercise, Olympic-style weightlfting and calisthenics. It was founded by Greg Glassman and Lauren Jenai in 2000. It was promoted as both a physical exercise philosophy, and also as a competitive fitness sport. CrossFit workouts incorporate elements from HIIT (high intensity interval training), strongman, calisthenics, gymnastics, powerlifting, plyometrics and Olympic weightlifting.

CrossFit, Inc. describes its strength and conditioning program as "constantly varied functional movements executed at high intensity across broad time and modal domains," with the stated goal of improving fitness, which it defines as "work capacity across broad time and modal domains." 

Hour-long classes at affiliated gyms, typically include a warm-up, a skill development segment, the high-intensity "workout of the day" (or WOD), and a period of individual or group stretching. Some gyms also often have a strength focused movement prior to the WOD. Performance on each WOD is often scored and/or ranked to encourage competition and to track individual progress. Some affiliates offer additional classes, such as Olympic weightlifting, which are not centred around a WOD.

CrossFit gyms use equipment from multiple disciplines, including dumbbells, barbells, gymnastics rings, pull-up bars, jump ropes, medicineballs, kettleballs, resistance bands, rowers, and various mats. The program is focused on constantly varied, high-intensity, functional movement which draw  upon categories and exercises such as weightlifting, powerlifting, plyometrics, bodyweight exercise, and aerobic exercises including indoor rowing, swimming and running.

According to the Greg Glassman, CrossFit is not a specialised fitness program, but a deliberate attempt to optimize physical competence in each of 10 recognized fitness domains. Those domains are: cardiovascular and respiratory endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance, and accuracy.

Indeed, CrossFit appeals to both men and women alike and a recent statistical analysis showed that CrossFit participants were almost equally 50% male and 50% female.

This program is ideal for those with a low boredom threshold as it incorporates a variety of exercises that can be done both inside and out of the gym. Through dedication to the program and a healthy diet, one can expect to achieve decent results within six weeks.