COUNT nouns refer to things that can be divided up into units which are separate and distinct from one another. They usually refer to what can be seen or heard.
Examples:
table chair word remark finger bottle award candidateNONCOUNT nouns refer to things that can't be counted because they are thought of as wholes which can't be cut into parts. They often refer to abstractions and occasionally have a collective meaning (e.g., furniture).
Examples:
anger furniture warmth leisure education courage progress weatherHere is an illustration that may clarify the concept. Think of the batter from which a cake is made. Before you put the batter into the oven, it can't be divided into parts because it's a thick liquid. Once it has been baked, however, it becomes solid enough to be cut into pieces. Noncount nouns are like cake batter; count nouns are like pieces of cake.
While such illustrations are of some use, they should not be taken too literally. It is not an accident that batter and cake were chosen to illustrate the mass/count distinction - in English batter is a mass noun and cake (in its count use - see "An Exception to the Rule" in the next section) a count noun! But different languages divide up their nouns into count and non-count in different ways, if they do so at all. Nouns that are countable in English may be noncountable in other languages, including your own, and vice-versa.
If you understand the difference in meaning between count and noncount nouns, you're ready to look at how it helps you make the grammatical choices listed above: 1) pluralizing, 2) using articles, and 3) using quantity words.
The talks will take place at Krannert.
There were bright lights and harsh sounds.
I dislike idle talk.
Light travels faster than sound.
The two possibilities in each half of the rule require different kinds of choices from you. If you know that a noun is either count or noncount you need to decide only if it is *possible* to pluralize the noun. On the other hand, if a noun can be both count and noncount, then you need to decide whether it is *appropriate* to pluralize.
To summarize, we can put the rule in a chart, like this:
Pluralizes with -s Doesn't Pluralize Count Noun XX Count Use XX Noncount Noun XX Noncount Use XX
a(n) the this these that those --------------------------------------------------------- COUNT Singular XX XX XX XX Plural XX XX