Pre Defined queries are some thing which helps us to navigate directly to particular screens or views. it helps in accessing the screens or views in faster manners

PDQ's are queries that are fired when we navigate to a particular view if there is a pdq defined on any of the applets present in that view.It can be specific to users i.e private or general i.e. public.It is stored in the user preference file.

It improves the performance by lim iting the amount of data being retrieved in the particular applet