RS: English teacher Lida Baker has the answer, starting with some background about nouns.
"There's what are called proper nouns, which are the ones that start with a capital letter, like Barack Obama or California or English. And then there are common nouns, which are the ones that start with a lower case letter, like a table or a radio or a puppy.
"So to answer the writer's second question first, names are proper nouns, OK? They start with capital letters. So a name is one kind of noun. Now the writer's first question is actually the much more interesting one."
AA: "And this has to do with the difference between countable and uncountable nouns."
LIDA BAKER: "Right, and uncountable nouns are also called non-count nouns. A count noun kind of is self-explanatory, because it's something that you can count.
"For example, 'microphone' is a countable noun. You can say one microphone, two microphones and so on. So anything that can actually be counted and that has an s to form the plural is a countable noun.
"Non-count nouns are ones where you cannot separate them into individual units. So 'water,' for example, is a non-count noun. You can't say 'one water' or love -- 'one love,' it sounds silly.
"Now, why is this an issue for people who are learning English? For one thing, we have nouns that represent whole groups, but within those groups there are individual items which are countable but they have a different name.
"Let me give you some examples. So we have a word like 'luggage.' It's correct to say 'I need to go buy some luggage.' But if you want to speak about an individual item within that category, you have to use the word suitcase or bag. 'I need to buy a suitcase, a bag.'"
AA: "Right. Or two suitcases would equal luggage.
LIDA BAKER: "Right, right."
AA: "Or three or four. Or even one bag."
LIDA BAKER: "It's very confusing. I'll give you one more example, something like the word 'food.' 'I'm going to the supermarket, I'm going to buy some food.' But 'I'm going to the supermarket, I'm going to buy three packages of spaghetti.'
"Or 'I need to buy apples, I need to buy eggs.' So the category 'food' is uncountable, but the items within that category are countable. So that's one of the reasons that count and non-count nouns are very confusing for people who are trying to learn English.
"Now, another problem is that a lot of nouns which are uncountable in English are countable in other languages, so when people are translating they end up making mistakes. And that's why it's so common for us English teachers to hear students making mistakes like 'Can you give me some advices.' Or 'I need some informations.'
"Or 'There's a lot of pollutions in that city.' Or 'I can't go out tonight because I have a lot of homeworks.' All those nouns are actually uncountable: advice, information, pollution, homework. Those words don't take an s because they're uncountable."
RS: Lida Baker says another complication is that some nouns are both count and non-count nouns, but the meaning changes.
LIDA BAKER: "Let's take an example like 'coffee.' And there's a store in my neighborhood that sells all kinds of different 'coffees.' In other words, many different varieties of coffee. OK, so there's an example where the same word is used in both a count and a non-count sense."
AA: English teacher and author Lida Baker in Los Angeles.
RS: And that's WORDMASTER for this week. With Avi Arditti, I'm Rosanne Skirble.