What are the different types of static stability?

What is the definition of stability in physics?

: the degree of stable equilibrium of a body (such as a suspended body, a floating ship, or an airplane in flight) capable of rotating out of its equilibrium position measured by the torque necessary to produce a given deflection.

An aircraft that has positive static stability tends to return to its original attitude when it's disturbed. Let's say you're flying an aircraft, you hit some turbulence, and the nose pitches up. Immediately after that happens, the nose lowers and returns to its original attitude.

Neutral static stability. An aircraft that has neutral static stability tends to stay in its new attitude when it's disturbed. For example, if you hit turbulence and your nose pitches up 5 degrees, and then immediately after that it stays at 5 degrees nose up, your airplane has neutral static stability.