Spanish has two simple past tenses. A quick rule of thumb:
- Preterite narrates a completed action with a clear start or end. Ayer comí paella.
- Imperfect describes background, habits, or ongoing states. De niño, comía paella los domingos.
Look for time markers: ayer, anoche, en 2010 → preterite. siempre, todos los días, cuando era… → imperfect.