Combinar vs. mezclar vs. unir

Although 'combinar', 'mezclar', and 'unir' may be translated as 'to combine' in English, they are used in different contexts in Spanish, each with unique nuances.

Combinar

This word generally implies bringing together different elements to achieve harmony or functionality. The emphasis is on accomplishing an aesthetic or strategic combination.
Voy a combinar esta falda con una blusa blanca.
(I'm going to combine this skirt with a white blouse.)
Podemos combinar nuestros recursos para terminar el proyecto.
(We can combine our resources to finish the project.)

Mezclar

'Mezclar' refers to the mixing or blending of multiple elements into one, often resulting in something new or different.
Mezcla la harina y el agua para hacer la masa.
(Mix the flour and water to make dough.)
No me gusta mezclar los negocios con el placer.
(I don't like mixing business with pleasure.)

Unir

'Unir' literally means 'to join'. It involves bringing together two or more entities to form a singular unit or bond.
Vamos a unir las dos mesas para la fiesta.
(Let's join the two tables for the party.)
El amor une a las personas.
(Love unites people.)

Summary

In conclusion, while 'combinar', 'mezclar', and 'unir' all imply some form of bringing together, their usage significantly differs. 'Combinar' typically involves assembling elements harmoniously, 'mezclar' involves blending elements into something different, and 'unir' implies joining together into a singular unit.