CrossFit is 'real world' fitness:

CONSTANTLY VARIED
What I love about CrossFit is that you never quite know what you are coming up against. Every workout is different in length and in the combination of exercises. One day you combine running with press ups and dips, the next day you are short stints on the rower combined with heavy deadlifts. And what that leads to is being FIT in the true sense of the word. Cardio will improve your endurance and stamina, weightlifting and powerlifting movements improve your strength, speed, power and gymnastic and body weight movements help you develop balance, coordination, flexibility and accuracy. CrossFit is all about specializing in NOT specializing in order to be FIT for all life can throw at you. Nothing comes close to helping you achieve this fitness like CrossFit.

HIGH INTENSITY
Because you are not concentrating on any one length or time of workout CrossFit gives you the ability to work all of the different energy systems in the body. A long distance runner will not cope with short, fast sprints in the same way that a powerlifter who lifts heavy weights wouldn’t have the cardio endurance to run 5 kilometres in a reasonable time. Because of the constant change in length of workout a CrossFitter is able to cope with anything thrown at them.

But it goes beyond that. With CrossFit you are always pushing the perimeters in each workout whether it is 5mins or 30mins helping you improve in the three energy systems in the body. Phosagen, Glyocgen and Oxygen. With this high intensity form of training you develop all round fitness. And because of the intensity of the sessions, workouts tend to be shorter so you are maximising the time you set aside for training. Where most people are finishing their warm ups, CrossFitters are finishing their workouts...

FUNCTIONAL MOVEMENT
All movements in CrossFit are functional which means they are movements that are multi-joint, using lots of muscles, and require a lot of energy to perform. They are movements that pertain to life unlike many of the machines and isolation exercises that are performed in a normal gym setting. These movements are unbeatable in producing strength and power as well as raising the heart rate. Combined with body weight and cardio components it doesn’t take long to realise you don’t have to be training for 45min-1hour to get an effective workout.

There is honestly no way to describe CrossFit. The only way to find out for yourself is give it a go.