Frequency: The word is one of the 700 most common words in English.
1.
If you refer to each thing or each person in a group, you are referring to every member of the group and considering them as individuals.
Each book is beautifully illustrated...
Each year, hundreds of animals are killed in this way...
Blend in the eggs, one at a time, beating well after each one.
DET: DET sing-n
•
Each is also a pronoun.
...two bedrooms, each with three beds...
She began to consult doctors, and each had a different diagnosis.
PRON
•
Each is also an emphasizing pronoun.
We each have different needs and interests.
PRON
•
Each is also an adverb.
The children were given one each, handed to them or placed on their plates...
They were selling tickets at six pounds each.
ADV: amount ADV
•
Each is also a quantifier.
He handed each of them a page of photos...
Each of these exercises takes one or two minutes to do...
The machines, each of which is perhaps five feet in diameter, are not the largest devices in the room.
QUANT: QUANT of def-pl-n
2.
If you refer to each one of the members of a group, you are emphasizing that something applies to every one of them.
He picked up forty of these publications and read each one of them.
QUANT: QUANT of def-pl-n [emphasis]
3.
You can refer to each and every member of a group to emphasize that you mean all the members of that group.
Each and every person responsible for his murder will be brought to justice...
They can't destroy truth without destroying each and every one of us.
PHRASE: PHR n, PHR of n [emphasis]
4.
You use each other when you are saying that each member of a group does something to the others or has a particular connection with the others.
We looked at each other in silence...
Both sides are willing to make allowances for each other's political sensitivities...
Uncle Paul and I hardly know each other.
PRON: v PRON, prep PRON