Quantity determiners (also known as quantifiers) are the "how much" or "how many" words in English. Their usage is strictly governed by whether the noun they modify is countable (dogs, chairs, ideas) or uncountable (water, advice, happiness).
Here is a breakdown of how to use them correctly.
1. The Countability Rule
Countable Nouns many, few, several a few Uncountable Nouns much, little a little Both some, any, a lot of, plenty of Examples: I have many books. She has little time. We need some water. The biggest hurdle in mastering quantifiers is matching them to the noun type.

Quantifier Type	Use with Countable (Plural)	Use with Uncountable
Small Amount	Few / A few	Little / A little
Large Amount	Many	Much
Number/Amount	A number of	An amount of
Flexible	Some / Any / A lot of	Some / Any / A lot of

Examples:
"I have many friends." (Countable)
"I don't have much time." (Uncountable)
"There are a few cookies left." (Countable)
"There is a little sugar left." (Uncountable)
2. "Few" vs. "A Few" (The Psychology of Grammar)
Adding the article "a" changes the emotional tone of the sentence.
A few / A little: Positive or neutral. It means "some" or "enough."
Example: "I have a little money" (Great! I can buy a coffee).
Few / Little: Negative or restrictive. It means "not many/much" or "not enough."
Example: "I have little money" (Oh no, I’m broke).
3. "Much" and "Many" in Context
In casual English, we often avoid using much and many in positive statements, opting for a lot of instead.
Formal/Negative/Question: "Do you have much work?" or "I don't have many options."
Casual Positive: "I have a lot of work" (Sounds more natural than "I have much work").
4. Distributive Determiners
These focus on the individuals within a group.
Each: Used when thinking about members of a group individually (usually for 2 or more).
Example: "Each student received a book."
Every: Used when thinking about a group as a whole (for 3 or more).
Example: "I exercise every day."
All: Refers to the entire group; requires a plural noun.
Example: "All students must attend."
5. The "Of" Rule
Generally, you use "of" when a pronoun or another determiner (like the, my, these) follows the quantifier.
No "of": "Most people like pizza."
With "of": "Most of the people in this room like pizza."
Pro-Tip: Never say "much of people" or "many of water." Always check your countability first!