Prueba vs. examen vs. test

The Spanish words 'prueba', 'examen', and 'test' are often used interchangeably as they all generally refer to an assessment of a person's knowledge or skills. However, there are subtle differences in their usage and connotations.

Prueba

'Prueba' is a general term for any test, examination, or trial. It is often used to refer to tests that are smaller or less formal than a major exam.
Vamos a tener una prueba de matemáticas mañana.
(We are going to have a math test tomorrow.)
Esta es una prueba de tu habilidad.
(This is a test of your ability.)

Examen

'Examen' typically denotes an official or formal testing process, such as an end-of-semester examination in a school context. It can also be used in medical contexts to refer to a diagnostic procedure.
Tengo un examen final el lunes.
(I have a final exam on Monday.)
El doctor está haciendo un examen físico.
(The doctor is doing a physical examination.)

Test

'Test' is borrowed from English and is used fairly interchangeably with 'examen'. However, it can often have the connotation of being a questionnaire or some sort of standardized test. It's also commonly used in the context of psychological or personality tests.
Fui al psicólogo y me hizo un test de personalidad.
(I went to the psychologist and they gave me a personality test.)
Este es un test para ver tu nivel de inglés.
(This is a test to see your English level.)

Summary

'Prueba', 'examen', and 'test' have overlapping but distinct usages in Spanish. While all can refer to forms of testing or examination, 'prueba' has a broader application and can be more informal, 'examen' generally refers to official exams in academic or medical contexts, and 'test', while interchangeable with 'examen', often suggests standardized questionnaires or psychological assessments.