Static is produced by the contact and separation of materials: shoes and floors, clothes and the human body, parts being moved on or from surfaces.

The generated charge will reside on the Body until it is discharged the familiar "zap" that all of us have experienced.

It's the "zap" that does the damage. If we can prevent any static charge from building up on the body, then there is essentially nothing to be discharged. A properly grounded esd wrist strap effectively prevents any static charge from building up.

Any static charge that would tend to be created is instantly "drained" by the esd wrist strap. The wrist strap maintains the potential equilibrium that is accomplished the hard way with the "zap".