ELS -
Extreme long shots are used to show a person or object and usually their surroundings.
LS -
Long shots are used to show an area, such as a tv studio and set, they are used a lot at the beginning and end of multi cam productions such as quiz shows.
MLS -
Mid long shots are used for the same reason as long shots.
MS -
Mid shots are used to show a person from their waist upwards, they are used in multi cam production when the host is maybe standing up and introducing the show.
MCU -
These shots are of the shoulders and head, and allow the viewer to see the persons reaction.
CU -
Used on someone's face to show their reaction,
ECU -
These are rarely used in multi cam productions such as quiz shows, and are usually found in film or soap operas when something dramatic happens,