The Third Conditional is a grammar structure in English that we use to talk about imaginary or unreal situations in the past and their possible results. It helps us express regret, criticism, or reflection about things that did not actually happen. The structure follows this pattern:

If + past perfect, would have + past participle
Example: If I had studied harder, I would have passed the exam.

In this case, the speaker did not study harder, and as a result, did not pass. The Third Conditional shows how the past could have been different, but wasn’t.

We can also use other modal verbs like could have or might have to show different levels of possibility. For example: If she had left earlier, she might have caught the train.

Overall, the Third Conditional is useful for reflecting on past situations and imagining alternative outcomes.