It depends which part of your legs you want to build. If you want to work on your quads you could always do wall sits if you don't have any weight equipment. If you want to build your caffs you can do wall jumps or box jumps if you don't have weight equipment
Exercises which incorporate vigorous or heavy lifting with the lower half of one's body are best to build leg muscles. http://www.bodybuilding.com/fun/wotw25.htm includes a list of exercises which can be effective in meeting this goal.
I'm Fat so i dont give one.
In my view cardio is the best exercise to do; in cardio also especially lungs and hamstring are the best choice for legs.
This depends on what muscles you want to exercise. Your legs contains many muscles including quadriceps, and tibialis. There are few exercises that can at the same time exercise them all. Probably one of the only exercises that can do that is swimming, because swimming works on all your muscles.
when one is running back and forth from one line to another working the lower legs muscles.
One of the best things that you can do is get a stationary bike. Not only will it help work out your legs and your core, but it will help you out to almost any need you want. I did some searching on it and that's what it came up with as the best result.
I think stomach exercises will build muscle and tighten existing ones. Once you have tightened your stomach muscles using one routine, change it up a bit and build muscles in another area.
There is no one right answer for this, but some very simple exercises can be found in the related links. These routines can help to strengthen the legs and ankles to prevent dangerous falls.
When you are looking for information about abdominal exercises one of the best places to start would be the local online forums. Members offer free advice and will be happy to explain the benefits of abdominal exercises.
Squats are one of the best.
Weight lifting is probably one of the best exercises to help you build muscle in your upper body, which in turn will build up your strength. You should aim to do weight lifting only one or two times a week, making sure to rest on in between days.
Aerobic exercises can contribute to weight loss pretty well by cutting body fat and increasing endurance and metabolism. They are one of the best next to cardiovascular and strength training exercising.