Step a great Aerobics class

The word aerobic literally means "with oxygen" or "in the presence of oxygen." Aerobic exercise is any activity that uses large muscle groups, can be maintained continuously for a long period of time and is rhythmic in nature. Aerobic activity trains the heart, lungs and cardiovascular system to process and deliver oxygen more quickly and efficiently to every part of the body.

Benefits of Aerobic exercises: Aerobic exercise conditions the heart and lungs by increasing the oxygen available to the body and by enabling the heart to use oxygen more efficiently.

Increased energy levels
Control of body fat.
Toned muscles and increased lean body mass.
Reduced stress, improved mental health and aid in sleeping.
(due to the release of endorphins in the brain)
Increased heart and lung efficiency
Reduced blood pressure, resting heart rate and risk of stroke or heart attack.

Different types of Aerobic classes:

Classes are generally rated as beginner, intermediate, and advanced. Choose the level that fits your condition.

Low-impact classes mean that one foot always stays on the ground. They are less intense than high-impact and may be more suitable if you are a beginner. Some classes are now called, "high-low" or "mixed-impact" which means they combine low and high-impact moves.

High-impact means both feet leave the ground, so there will be jumping and balance moves. Stick with lower-impact and more gentle and rhythmic dance classes.
Step aerobics moves that incorporate up and down movements on a platform (step). Step moves include basic steps, lunges, turn steps, V-steps, over-the-top steps, L-steps and knee-lifts.
Super step aerobics is similar to step aerobics but using a faster tempo. Intended for advanced classes, Super Step aerobics revolves around half-time power moves (squats, forward lunges, isolation holds, etc.), as well as the basic step moves.
Interval alternates high and low intensity movements, which might alternate, step and aerobic combinations to challenge the cardiovascular system.
Cardio is the portion of the class designed to work the cardiovascular system (see 1-7 above). The cardio segment is approximately 35 minutes long.
Post-cardio is the movements performed after the cardio (i.e. aerobics. step etc.) segment of a class. These help the cardiovascular system transition from a high intensity workout to normal activity, and bring breathing and heart rate back to normal levels.
Cool down movements designed to lengthen the muscles after exercise return to the cardiovascular system to resting levels. A cool down typically combines stretching with slow, deep breathing and slow rhythmic arm movements. A cool down is approximately 5 minutes long.
Experiment until you find the classes that work best for you.

Aerobic training workouts and routines:

The simplest method of starting is just that, simple. Select the number of minutes you'd like to walk for (let's say 20 minutes for your first walk) and head out the door or step on the treadmill and go for it.
It's not important how fast you do it; it's just important that you attempt to complete the time. If you find 20 minutes is too ambitious, then start with less. Again, the most important thing is to get started. You can always add more later on.
You walk or jog out for five minutes, stop, and return to your starting place. That's it. 10 minutes and off you go about your day! If you feel ambitious you can try seven and a half out and seven and a half back, or even 10 out and 10 back.

Interval training is more intense than simple aerobic training. It's a very effective way to increase your fitness level, but it's tough, and so I recommend holding off until you build up to 20-30 minutes of aerobic exercise. The idea to intervals is to set up work to active-rest ratios, and as you get more fit, decrease the active-rest interval and increase the work interval. To do it, you start at your usual speed for five to eight minutes, then increase the speed to the work interval for one to three minutes, then slow down to your usual speed for a few minutes to catch your breath and then you repeat the cycling for the duration of your workout.
The general rule for increasing aerobic activity is 10% per week. Interestingly, there's no evidence to suggest that a 10% increase is the safest and most effective amount of time to increase, but that's the rule of thumb and it seems to work pretty well.

For good cardiovascular fitness it is generally recommended to exercise 3 to 5 times a week and for 30-60 minutes, not including warming up at the start and cooling down at the end.

Aerobic Exercise at home: It is not essential to join a gym or to go out in the middle of winter to get an aerobic workout. There are a number of exercises that you can do in the privacy of your own home.

Put on your favorite CD and dancing around the living room or giving the house a vigorous clean.
There is also an ever increasing array of affordable home fitness products available, such as steps, skipping ropes , rebounders, dance mats that you can use with your games console and exercise videos so that you can work out with your favorite celebrity.
Even taking a few extra brisk walks can be enough to improve fitness and receive the benefits of aerobic exercise. Running, jogging or going out for a bike ride when the weather's nice are all good forms of aerobic exercise.
Pretty much any exercise is better than no exercise at all. The real benefits of aerobic exercise come from constant movement.

Make sure that you listen to your body. It's ok for muscles to be tired, but if they or your joints start to feel sore or breathing becomes uncomfortable slow down or stop to ensure that you are in a fit state for your next session.

(Sources: shapefit.com, weightlossresources.co.uk, medicinenet.com, k2.kirtland.cc.mi.us)