Tense difference ; subordinate clause "will" or "would"

Question

I'm not a native speaker. So I'm confused with the tense as the following sentence.

1.I heard that they would hold a party.

2. I heard that they will hold a party.

The tense in main sentence is the past, I knew the tense of subordinate clause is the past before the present in 1 sentence. Is it correct?

In 2 sentence, the tense of subordinate clause is the future, and the event doesn't still happen. Is it correct?

By the way, in reported speech according to an English site, the tense of subordinate clause "they would hold a party" is also the future. Is it accurate? I'm not sure what is right?

Is there anyone who explain it to me?

Answer 1

Sentence 2 is easier to deal with. The main clause is in the past tense, and the subordinate clause is in the future tense. That's pretty clear.

In sentence 1, the main clause is also in the past tense. However, the subordinate clause uses the modal auxiliary verb "would". This is sometimes called a "preterite" form, sometimes called the past tense, sometimes called the future-in-the-past tense, etc. In other words, tenses with modal verbs can be tricky, and there are several possible interpretations. I recommend that you research the use of the modals "would" and "will"; there are plenty of books, websites, etc. that discuss this in much greater depth than could possibly be covered here.

Answer 2

You are right, the "would" in "they would hold a party" is in the past tense, while the "will" in "they will hold a party" is in the future tense. Here are some other examples:

"I heard that they would hold a party yesterday, so I came to their house last night."

"I heard that they will hold a party tomorrow, so I will come to their house tomorrow night."

"Would" is used as the past tense of "will", but it's also used for hypothetical, conditional, or desired situations, which obviously have not yet occurred (and might never occur). This could be what the websites you saw mean by "would" sometimes referring to the future. For example:

"They would hold a party, if they had the money for it." (conditional event)

"I would like to go to their party, so I hope they invite me." (desired event)