Korean confusion warning: 있다 and 이다. These are two of the most important bits of language in Korean, yet they are easy to get muddled up when you first start learning.
있다 and 이다 correspond roughly to the English verbs 'to have', and 'to be'. However, the way we use the verbs 'to have' and 'to be' in English is quite different to the way we use 있다 and 이다 in Korean. Don't panic, though - you'll hear both of these all the time, so it's easy to pick up when and how to use them.
Here are a few usage points to consider:
1. 이다 plus adjectives? X
In English we use the structure 'subject + be + adjective', eg. 'I am pretty' (yeah, very useful example).
In Korean, instead of using 'adjectives', we use 'descriptive verbs'. So the structure is:
subject + subject marker particle + descriptive verb
eg. '나는 예뻐' (나 + 는 + 예쁘다)
There is no '이다' in this sentence, as '예쁘다' already means 'to be pretty'.
So it's important to remember that '이다' cannot 'describe' a characteristic. You can't 'be' an adjective in Korean. When it comes to 이다, you can only 'be' a noun.
2. Location plus 있다
When you want to say 'Where is something?' or 'It's there,' in Korean, you usually need to use the verb 있다. For example, '학교가 어디에 있어요?' (Where is the school?). In this case, 있다 can be translated not as 'to have', but rather as 'to exist (somewhere)', so the sentence literally means something like 'Where does the school exist?' Here are some more examples:
'책상 위에 뭐가 있어요? -- 책이 있어요.'
'What's on the desk? -- There's a book.'
(Could be translated as 'The desk has what on top? -- It has a book.', or 'What exists on the desk's top? -- a book exists')
'친구들이 한강에 있어'
'My friends are at the Han river.'
Of course, it's not as simple as just always using '있다', because there are some cases when '이다' (예요/이에요) is used to talk about location (you'll hear '어디예요?' a lot). This can get a little complicated, but generally it's best to use 있다 to describe the location of an object or person, meaning of course that the object or person 'exists' in that location.
In order to understand the reason for all of this, you need to know that 있다 is a verb, but 이다 is not actually a verb, it's something else and has a specific function:
You can think of 이다 as meaning 'to be equal to', which may make it easier to distinguish when you can and can't use it. I think that the main difference between this and the English verb 'to be' is that in English you can say '(noun) is (adjective)' or '(noun) is (somewhere)', but in Korean when using 이다 you can only say '(noun) is (noun)' or '(somewhere) is (somewhere)', otherwise you'll have to use a structure without 이다. I'm still trying to get my head around this myself!
있다 on the other hand is not too difficult to understand really, but it has a few different functions - as I said before, it usually means either 'to have' or 'to exist (somewhere)', or something to that effect, and it's a regular verb. Makes sense after a while!