El condicional
(The conditional)

The Spanish conditional is used in most of the same contexts as the English conditional, which is formed using 'would' + verb.

Yo no saldría a esta hora = I would not go out at this hour

Te dije que el avión llegaría tarde = I told you that the plane would arrive late

The only exception is that in English, the "would" construction is often used to talk about something one used to do in the past, often accompanied by the word "always", as in "When I was little, I would always play with my sister". This is expressed by the imperfect in Spanish: Cuando era niña, yo siempre jugaba con mi hermana.

Like the future, the conditional of regular verbs is formed by adding the appropriate endings to the infinitive and there is no difference between -ar, -er, and -ir endings:

daría daríamos leería leeríamos iría iríamos
darías daríais leerías leeríais irías iríais
daría darían leería leerían iría irían

The verbs that are irregular in the futuro simple have the same irregular stems in the conditional; the 3 groups are repeated here:

1. Verbs that drop the last vowel of the infinitive: caber, haber, poder, querer, saber

poder > podr- podría podríamos
  podrías podríais
  podría podrían

2. Verbs that drop two letters of the infinitive: decir, hacer

decir > dir- diría diríamos
  dirías diríais
  diría dirían

3. Verbs that drop the last vowel of the infinitive and insert a d: poner, salir, tener, valer, venir

tener > tendr- tendría tendríamos
  tendrías tendríais
  tendría tendrían