Reflexion

Reflexion, often written reflection in American English, is a term with several related meanings. In everyday language it denotes the act of turning attention back onto something, or the process of careful thought. In scientific contexts it commonly refers to the return of waves, such as light or sound, after they strike a surface.

In optics and acoustics, reflection describes the redirection of a wave at a boundary between media. The law of reflection states that the angle of incidence equals the angle of reflection measured relative to the surface normal. Specular reflection produces coherent, mirror-like images, while diffuse reflection scatters rays in many directions. Total internal reflection occurs when a wave is completely reflected within a medium.

In geometry, a reflection is an isometry that fixes a hyperplane pointwise and reverses orientation. In two dimensions, reflection in a line; in three dimensions, reflection in a plane. Reflections generate symmetry groups, and the composition of two reflections is a rotation, yielding connections to crystallography and group theory.

In philosophy and psychology, reflexion or reflection denotes contemplative consideration, self-examination, or the process of thinking about one’s beliefs and actions. In social science, reflexivity refers to awareness of how the observer’s position, methods, and assumptions influence inquiry and interpretation.

In computing, reflection (often termed reflection or reflexion in some languages) is the capacity of a program to inspect and modify its own structure and behavior at run time. It underpins features such as dynamic type inspection and invocation of methods. Many languages, including Java and C#, provide reflection APIs to support these capabilities.