In general, 'the' is used with plural countable nouns when referring to something which has been mentioned before.
e.g. Fallen leaves covered the ground. The leaves rustled as we walked.
Students and teachers began leaving the building. The students were
talking and laughing.
In these examples, the first time the words leaves and students appear, they are not preceded by determiners, because the things referred to have not been mentioned previously. The second time the words leaves and students appear, they are preceded by the, since the things referred to have already been mentioned.
'The' is not used with plural countable nouns when it is used in general statements.
e.g. Foreign students work hard to learn English.
Teachers love helping students.
There is much more to be mentioned here. Let me know if I am on the right track.
Originally Posted by gemini