AI does not understand your question and then write a reply. AI predicts one word at a time. AI looks at all the words that came before, and picks the most likely next word. Then AI looks at everything again, including the word it just picked, and predicts the next one. This keeps going until the full response is built.
This means every word AI has seen so far shapes what comes next. The previous words are the context. Change the context, change the output.
This is why what you type matters so much. Your words are the context AI uses to predict everything that follows.
Fill in the blank below
Try with your brain
She checked the time on her ___
Try with your brain
She checked the pressure on her ___
Same sentence, one word changed. Your brain predicted "watch" for the first and "tires" for the second. You did not think about it. The word before the blank changed what your brain predicted. This is exactly how AI works. AI reads the words before and predicts what comes next. Change one word and the prediction changes completely.