I don't think there is anything wrong with asking a question found on a different website. Especially if you are curious for the answer. That being said, the question is too vague to be answered properly. Sieges have varied greatly depending on the era taken place and the technology available. The Siege of Acre during the Third Crusade is going to a provide a different experience for the defenders than the Siege of Vienna in 1683 or the Siege of Tobruk during WWII. You could identify general themes such as starvation, disease, diplomacy and defence tactics. However, how these are executed is going to vary too widely depending on the period to give a concise answer. The question could be improved by asking about a specific period rather than trying to describe sieges as a whole.