Learn Hardcore Spanish (Latin America): El festival ha sido muy divertido.

Ha sido is in the present perfect tense, which indicates the action has relevance or effect in the present moment. Meanwhile, fue (the preterite tense) implies the action is fully completed in the past with no direct impact on the present. Using ha sido can suggest you're still thinking about or feeling the result of how fun the festival was.

Is it correct to say El festival fue muy divertido in casual conversation?

Yes, you can say that if you want to speak about the event simply as a completed past action. However, El festival ha sido muy divertido puts more emphasis on the experience’s continuing relevance, such as how you’re still talking about it or still feeling excited about it.

Why do we use the verb ser (in the participle form sido) instead of estar (such as estado)?

Ser often focuses on characteristics or inherent qualities, whereas estar tends to highlight temporary states or conditions. Calling a festival divertido with ser indicates it was/has been an inherently enjoyable event. Using estar would be less common in this context, because you would be describing a fleeting condition rather than an essential quality of the festival.

Why do we say muy divertido instead of mucho divertido?