atplerry 0 Junior Poster in Training

Hello i am designing a website that the security need to be taking care of now i am in thought on what decision to make on either using Query String OR session/cookies but i dont know the use of query string but i have use session to complete the website i need your contribution stating the danger in using session in the website and send me a query string code to retrive value from the database and passing the value from one webpage to the other
Thanks your contribution will mean a lot to me!