 Area moments of inertia are a measure of the distribution of a two-dimensional area around a particular axis. Fundamentally, the portions of a shape which are located farther from the axis have a greater affect than the parts which are closer. The primary application is in structural engineering and machine design where they are used to determine a structural member’s stiffness. Another application is in Fluid Mechanics where they are used to determine the effect of pressure on a submerged surface. We will use the symbol $$I$$ for this property, along with a subscript to indicate the specific axis, so for example, $$I_x$$ would indicate the “Area moment of inertia with respect to the $$x$$ axis.”
The mass moment of inertia you learned about in Physics is not the same as the $$area$$ moment of inertia in Statics!
This can be confusing since both are commonly shortened to “moment of inertia” and both use the same symbol, $$I\text{.}$$ They have different units however, and the intended moment of inertia can easily be determined from context or with a unit analysis.