If your looking to develop your calf workouts then understanding your anatomy will help so you can create stronger more defined muscles.
The bottom portion of your leg is composed largely of your calf muscle which, while it is a small muscle, plays a predominant role in many activities.
Also to create appropriate calf workouts you need to known its movement & function, as one of the most important functions of the calf muscle is to help support and stabilize the ankle joint. If you have very weak calf muscles, you might find that you are more prone to ankle rollovers. Runners in particular should be concerned with developing strong defined calf muscles through their workouts as they can also help to prevent the occurrence of shin splints, which is quite a debilitating condition.
Since you use your calf muscles in almost every movement you make while standing, they are going to be constantly partially tensed and would therefore be classified as more of an 'endurance' muscle. Most times when training them you can afford to take your rep ranges slightly higher because of this. However, if muscle strength and size increases are still a main goal, you need to be lifting heavy weights. Doing hundreds of raises without any weight may increase their resistance to fatigue but it isn't going to do a whole lot in terms of maximum levels of strength.
This muscle also can become tight quite easily so be sure to stretch it out thoroughly both before and after any running activities. You can perform a stretch by simply placing your ankle up against a wall so that the pad of your foot is raised and you are feeling the stretch in the back of the leg. Alternatively you can also stand off a step so that your body weight falls off the back of your heal such that the muscle is lengthened and stretched that way.
So be sure to include exercises for this muscle regularly. It is one that is too commonly overlooked, which would be considered a major workout error.