New students and a lot of social dancers don't take footwork very seriously. They think footwork is for competition dancers so the judges have something to do. Every thing we do in ballroom dancing has a reason and footwork is definitely one of them. The footwork defined for ballroom elements is designed to make the partnership movements as easy and natural as possible and create the character and feeling of the dance. Don't forget that we are trying to move a two-headed, four-legged animal around the floor.
First of all let's define "footwork". Footwork is the part of the foot in contact with the floor on each step (e.g., toe, ball, heel, flat).
Toe: the end of the shoe, (a backward step in Smooth dancing would cause a toe step).
Ball: the forward part of the shoe is on the floor (heels off the floor).
Heel: the forward part of the shoe is off of the floor (the heel step rolls from heel to flat).
Flat: the whole shoe, front and back is touching the floor.
It is very important that you realize many instructors use the terms "toe" and "ball" interchangeably. If it isn't apparent what the instructor means, don't be afraid to ask which he/she is talking about.
Traveling around the floor requires heel leads. Flat or toe steps cause short and restrictive movements. There are three types of heel steps in Smooth and Standard dancing. A straight heel, an inside edge heel and an outside edge heel. When you step straight ahead in Foxtrot, for example, this would result in a straight heel step. If you step forward outside partner in Foxtrot, an outside edge heel step would result. A step to the side and slightly forward (such as in Tango) would result in an inside edge heel step. The resulting footwork is because of the body's position and the direction of the movement not because you placed your heel in a specific position with your foot and ankle.
A basic rule for footwork is "ball to ball and heel to heel". This means that the most natural and efficient way to take a ball step is from a previous ball and the same for the heel step. If this is true than how do you get from a heel to a ball and vice versa? Obviously there must be transition steps. These are heel steps rolling through the foot to a ball and ball steps lowering to a flat.
International Quickstep is a very good example to use when talking about footwork. Quickstep's speed requires precise footwork to maintain speed, control, and partnership. Quickstep uses controlled falls to change directions quickly and easily with little effort. Let's use the element the "quarter turn to the right" as an example.
The pattern is: forward(right foot) side left together backward
The footwork is: heel-ball ball ball ball flat
The timing is: slow quick quick slow
You will notice that the transition steps from heel to ball and ball to heel are executed on a slow so there is time to complete the transition. The quicks are executed on the ball of the foot. The backward step is really a controlled fall from a ball to a ball-flat. The pattern feels like you rise slightly on the first step, move level to the side on rise (on the side together steps) feeling slightly backward and then gently falling to the ball-flat backward step. The backward movement does not feel like a deliberate backward step. It feels more like you are regaining your balance from a very slight backward fall.
This is a very simple example of how footwork is involved with controlled movement of the infamous two-headed, four-legged animal.