Classical mechanics discusses the behaviour of macroscopic bodies under the influence of forces (without necessarily specifying the origin of these forces). If it's possible, USE MORE SPECIFIC TAGS like [newtonian-mechanics], [lagrangian-formalism], and [hamiltonian-formalism].
Classical mechanics refers to the classical (i.e., non-relativistic, non-quantum) study of physics. Three major formulations of classical mechanics are Newtonian mechanics, Lagrangian mechanics, and Hamiltonian mechanics. The latter two are rather useful in extensions to Classical Mechanics, Special and General Relativity, Quantum Mechanics, and beyond. Rotational dynamics, Statistical Mechanics, and Fluid Mechanics are subsets of Classical Mechanics.
However, the broader term, classical-physics, is often also used for special-relativity and general-relativity, as they also use the principle-of-least-action.
When to Use This Tag
Use classical-mechanics when discussing general concepts of classical mechanics, i.e. the behaviour of macroscopic bodies under the influence of forces (without necessarily specifying the origin of these forces).
Use this tag only if newtonian-mechanics, lagrangian-formalism, hamiltonian-formalism, fluid-dynamics, statistical-mechanics, rotational-dynamics and the like are too specific. In general, you should not use classical-mechanics together with general-relativity or quantum-mechanics.
Overview
Classical mechanics is the study of the movement of bodies under the influence of forces. In the absence of either movement or forces, the subtopics statics and kinematics arise, whereas the ‘complete’ subject is often dubbed dynamics.
For point particles/bodies, there are three equivalent approaches to deriving the trajectories of said bodies: newtonian-mechanics based on Newton’s Laws, lagrangian-formalism based on the variational principle and hamiltonian-formalism following from Legendre transformations of Lagrangian mechanics.
More advanced subtopics are fluid-dynamics for the study of moving many-body fluids (liquids, gases), statistical-mechanics for the derivation of macroscopic laws from microscopic principles (often making use of the Hamiltonian formalism) and rotational-dynamics for the study of rotating solid bodies.
Textbooks
Structure and Interpretation of Classical Mechanics, by Sussman, Wisdom, Mayer.
Physics for Scientists and Engineers with Modern Physics, by Jewett, and Serway.
Classical Mechanics, by Goldstein, Poole and Safko.
Mechanics, by Landau and Lifshitz.