This section is from the Openstax University Physics: Volume 1 online textbook.
In physics, work is done on an object when energy is transferred to the object. In other words, work is done when a force acts on something that undergoes a displacement from one position to another. Forces can vary as a function of position, and displacements can be along various paths between two points. We first define the increment of work $\text dW$ done by a force $\mathbf F$ acting through an infinitesimal displacement $\text d\mathbf r$ as the dot product of these two vectors:
Is it simply just a very small displacement?