I got the feeling, that necroposting is frowned upon at physicsforums. My question is what constitutes necroposting and how to avoid it? I am a beginner so don't know rules in details. Suppose for instance, I have a doubt regarding a thread which hasn't been discussed for 3-4 months. The OP seems to be satisfied with the replies , but I have a few doubts in the reply. Should I create a new thread and quote the old thread ? Or , when it ok to post in such a thread ? Note - the thread in which i wish to post isn't speculative in nature. it is straight maths.