QUARTERS -- Calling the Quarters, Guardians, Guardians of the Watchtowers, or whatever title they are given are used when casting a circle. Depending on the belief, they are the cardinal directions, directions and elements, elementals, protective spirits (hence Guardians), some have the elements separate from the Guardians or the Guardians add their elemental power to the circle.
Whether They are evoked, invoked, or convoked, it is the rule of thumb not to call forth something that is not understood fully.
Usually the elemental energy is used to enhance the magic performed in the circle.
QUERENT -- In a tarot reading, this is the person who is getting the the reading. Can also be called the Seeker. The querent will have a specific tarot card that represents him/her in the spread (the layout of the cards), which is called the Signifier or Significator.
Disclaimer: None of these pictures belong to me. I found them on Google.