Tacón vs. taco
When referring to the heel of a shoe in Spanish, the choice between tacón and taco depends largely on geography and the specific part of the shoe. While tacón is the standard, universal term for a traditional heel, taco acts as a regional synonym in parts of South America and also refers to specific functional heel pieces.
Tacón
The word tacón is the universally accepted and understood Spanish translation for the heel of a shoe. It is used in almost all Spanish-speaking countries to refer to the elevated back part of a shoe, and by extension, refers to women's high heels as a style of footwear.
Ella nunca usa zapatos de tacón porque le duelen los pies.
(She never wears high heel shoes because her feet hurt.)
El zapatero reparó el tacón de mi bota derecha con mucho cuidado.
(The cobbler repaired the heel of my right boot very carefully.)
Me compré unos botines con un tacón muy bajo para caminar cómoda por la ciudad.
(I bought some ankle boots with a very low heel to walk comfortably around the city.)
Se escuchaba el eco de cada tacón al caminar por el pasillo vacío.
(The echo of each heel was heard while walking down the empty hallway.)
Ana prefiere usar zapato de tacón aguja para las fiestas de gala.
(Ana prefers to wear a stiletto heel shoe for gala parties.)
Se le rompió un tacón justo antes de entrar a la reunión de trabajo.
(Her heel broke right before entering the work meeting.)
El baile flamenco tradicional requiere zapatos con un buen tacón para lograr el sonido del zapateo.
(Traditional flamenco dancing requires shoes with a good heel to achieve the sound of the footwork.)
Un tacón ancho siempre ofrece mucho más soporte a la espalda que uno delgado.
(A wide heel always offers much more back support than a thin one.)
Taco
The word taco frequently means the heel of a shoe in South American countries like Argentina, Chile, and Peru. In broader Spanish terminology across the globe, taco refers more specifically to the small replaceable rubber tip at the very bottom of a heel, or the studs and cleats found on the bottom of sports shoes.
En Argentina es muy común usar zapatos de taco alto para salir a bailar de noche.
(In Argentina it is very common to wear high heel shoes to go out dancing at night.)
Tienes que cambiar el taco de ese zapato porque la goma ya está completamente gastada.
(You have to change the heel tip of that shoe because the rubber is already completely worn out.)
Ayer me resbalé en la escalera porque perdí el taco izquierdo de mi bota.
(Yesterday I slipped on the stairs because I lost the left heel tip of my boot.)
Ella tiene una colección impresionante de botas de taco en su armario.
(She has an impressive collection of heel boots in her closet.)
Caminar con tacos altos por las calles empedradas de la ciudad vieja es muy difícil.
(Walking with high heels on the cobblestone streets of the old city is very difficult.)
Para jugar al fútbol en césped natural mojado, necesitas un buen zapato con taco.
(To play soccer on wet natural grass, you need a good shoe with a cleat.)
Los jugadores limpiaron el barro pegado en cada taco de sus botines al terminar el partido.
(The players cleaned the mud stuck to each cleat of their boots at the end of the match.)
Me encanta el diseño de este zapato oscuro, pero el taco me resulta demasiado grueso y pesado.
(I love the design of this dark shoe, but the heel is too thick and heavy for me.)
Summary
Use tacón to be safely understood in any Spanish-speaking country when talking generally about shoe heels or high-heeled footwear. Reserve taco for regional conversations in South American nations where it acts as a direct synonym, or when specifically describing the rubber protective tap at the bottom of a heel and the cleats on athletic shoes.