The Spanish preposition tras, usually meaning "behind" or "after," isn't a particularly common preposition. In fact, you could probably get by without even using it, as the prepositional phrases detrás de ("behind" in location) and después de ("after" in time) can usually be used instead. Tras is more common in writing than in speech.
Even so, tras has significant use in journalese (it's a shorter word to use in headlines) and in a few phrases such as uno tras otro (one after the other) and día tras día (day after day).
Here are the most common meanings of tras, along with examples of its use:
- After (in time): Se degradó la libertad de prensa tras la elección. (Freedom of the press was diminished after the election.) El restaurante abre de nuevo tras ser cerrado. (The restaurant is opening again after being closed.)
- Behind (in location): Tras las puertas cerradas puede haber violencia. (Behind closed doors there can be violence.) Necesita contraseña para participar en las conversaciones tras la pared de protección corporativa. (You need a password in order to participate in conversations behind the corporate firewall.)
- After (in the sense of being in pursuit of): Iba tras las riquezas. (He was after riches.) El perro salió tras ella. (The dog went after her.)