For any request, a web browser would first check its local disk cache for a local copy of web page at a given URL.The percentage of accesses which result in cache hits is known as the hit rate.See
http://en.wikipedia.org/wiki/Cache
Server side scripting generally involves connection with database(user database, shopping cart, etc) and adding dynamic content to the website. ASP and JSP are some of the main languages used for this purpose.
Shopping cart contains the list of items that the user has selected to purchase. These can be added/deleted at any time. The final cost of the items is decided at the time of checkout/making payment.
Pls. let me know if you require anything else.