Collective Noun

A group of people, animals or a collection of things taken as a whole is collective noun.

1:-it is not a noun of multitude 

As

The jury consists of twelve persons.

The jury were divided in their opinions.

2:-people,the gentry, the elite, the police etc are always plural.

3:-Machinery, luggage, furniture, scenery, clothing etc are always singular.

4:-flock, audience, committee, government,bench,fleet etc are like common noun singular & plural.

5:-Microsoft,Sony,Apple,CNN,WHO,, Interpol,the BBC & the United Nations etc are both proper & collective. 

Example:-

Swarm a group of flies.

Pack a group of dogs.

School a group of fish.

 Other

Set,class, team, troop,bevy,flock, herd, piece, bunch, grove, library,album,heap,hive, cartoon, government, mob,mass, family, staff, crew army,gang, colony, band board etc