Rigidbody, colliders, triggers, physics queries and collision handling.
Rigidbody
Colliders
Triggers
Collision Events
Raycast
SphereCast and BoxCast
OverlapSphere and CheckSphere
LayerMask and Collision Matrix
Physics Material
Collision Detection
FixedUpdate and Physics Timestep
2D vs 3D Collisions
Ignoring Collisions
Common Physics Mistakes
Complete Raycast Interaction Example