Also known as the past continuous, the imperfect verb tense is used to describe events taking place in the past without regards to when the event began or ended.

The imperfect tense describes actions that:
• were happening,
• used to happen,
• or happened regularly in the past and on going.

The simple past is more akin to the English past tense, in that it specifies an exact time the action took place. It however is used primarily in writing and formal occasions.

The most common way of expressiving past actions is the passé composé (compound past) tense, which is formed with the past participle and the verb avoir (to have).

The examples below illustrate the difference with the word parler:

Imperfect
Elle parlait.
She was talking.

Simple Past
Elle parla.
She talked.

Compound Past
Elle a parlé.
She has talked.