Common categories of noncount nouns include types of food (cheese, meat, bread), solids (dirt, salt, chalk), liquids (milk, juice, gasoline), gases (methane, hydrogen, air), and abstract ideas, including emotions (democracy, gravity, love).

Another category of noncount nouns is mass nouns, which usually represent a large group of countable nouns (furniture, mail, clothing).

The only way to count noncountable nouns is to use a countable noun with them, usually to indicate a quantity or a container.

one piece of furniture, two quarts of water, an example of jealousy

Noncount nouns, such as advice, are never preceded by an indefinite article; they are often preceded by some.

When noncount nouns are general in meaning, no article is required, but when the context makes them specific (usually in a phrase or a clause after the noun), the definite article is used.

Use the with a specific count or noncount noun mentioned before or familiar to both the writer and the reader.

She got a huge box in the mail. The box contained oranges from Florida. [The is used the second time the noun (box) is mentioned.]

Did you feed the baby? [Both reader and writer know which baby.]

Use the before specific count or noncount nouns when the reader is given enough information to identify what is being referred to.

The furniture in my apartment is old and faded. [Specific furniture]

Use the before a singular count noun to state a generality.

The dog has been a companion for centuries. [The dog refers to all dogs.]

Use the before some geographical names.

Collective Nations: the United States, the United Kingdom

Groups of Islands: the Bahamas, the Canary Islands

Large Bodies of Water (except lakes): the Atlantic Ocean, the Dead Sea, the Monongahela River, the Gulf of Mexico

Mountain Ranges: the Rockies, the Himalayas

Use the or another determiner when plural count nouns name a definite or specific group; use no article when they name a general group.

Hal is feeding the horses in the barn, and he has already fed his cows.

Horses don’t eat meat, and neither do cows.

Use a or an with a nonspecific, singular count noun when it is not known to the reader or to the writer.

Jay has an antique car. [The car’s identity is unknown to the reader.]

I saw a dog in my backyard this morning. [The dog’s identity is unknown to the writer.]

Use a or an when the noun is first used; use the when it is repeated.

I saw a car that I would love to buy. The car was red with tan seats.

Use some or no article with general noncount or plural nouns.

In means “within” or “inside of” a place, including geographical areas, such as cities, states, countries, and continents.

I packed my books in my backpack and left to visit my cousins in Canada.

Where in emphasizes location only, at is often used to refer to a place when a specific activity is implied: at the store (to shop), at the office (to work), at theater (to see a play), and so on.

Angelo left his bicycle in the bike rack while he was at school.

On means “on the surface of” or “on top of” something and is used with floors of buildings and planets. It is also used to indicate a location beside a lake, river, ocean, or other body of water.

The service department is on the fourth floor.

We have a cabin on Lake Michigan.

In, on, and at can all be used in addresses. In is used to identify a general location, such as a city or neighborhood. On is used to identify a specific street. At is used to give an exact address.

We live in Boston on Medway Street.

We live at 20 Medway Street.

In and at can both be used with the verb arrive. In indicates a large place, such as a city, state, country, or continent. At indicates a smaller place, such as a specific building or address. (To is never used with arrive.)

In indicates the span of time during which something occurs or a time in the future; it is also used in the expressions in a minute (meaning “shortly”) and in time (meaning “soon enough” or “without a moment to spare”). In is also used with seasons, months, and periods of the day.

He needs to read this book in the next three days. [During the next three days]

I’ll meet you in the morning in two weeks. [Two weeks from now]

On is used with the days of the week, with the word weekend, and in the expression on time (meaning “punctually”).

Let’s have lunch on Friday.

At is used in reference to a specific time on the clock as well as a specific time of the day (at night, at dawn, at twilight).

We’ll meet again next Monday at 2:15 p.m.