Some forces do work that depends only on the starting and ending configurations, not on the path taken between them. Such forces are conservative.

For a conservative force, a potential energy $U$ can be defined so that

$$\Delta U=-W_{\mathrm{cons}}.$$

If the force does positive work, the associated potential energy decreases; if work is done against the force, the potential energy increases.

Potential energy belongs to a configuration

Potential energy is not stored in one isolated object by itself. It belongs to the configuration of interacting objects or fields.

For example, near Earth's surface the gravitational potential-energy change is

$$\Delta U_g=mg,\Delta h.$$

For an ideal spring,

$$U_s=\frac12kx^2$$

relative to the equilibrium position.

Path independence

For a conservative force, the work between two points is independent of the route taken. Equivalently, the total work done by that force around a closed path is zero.

Friction is an important example of a nonconservative force: its work depends on the path length and converts mechanical energy into other forms.