Grammar details: Definite and Indefinite
There have been quite a few questions about the use of definite vs. indefinite conjugation. I thought I'd write a little more here in addition to the Tips & Notes that are already provided in case a little more explanation or more examples would be helpful. I've borrowed and adapted from the textbook "Learn Hungarian." This won't be perfect or include every possible detail, but maybe it's helpful anyway.
Overall, it seems simple enough: the definite conjugation is used when the verb has a definite object and the indefinite conjugation is used when there is no object or only an indefinite one.
Ex. (No object; indefinite conjugation)
Jól látsz? - Can you see well?
Igen, jól látok. - Yes, I can see well.
Ex. (Definite conjugation)
[Said while pointing to an object] Látod? - Do you see it?
Látom. - I see it.
The definite object in this case is not even a word that appears in the sentence! The verb látod itself is using the definite conjugation to tell you that I'm asking about a specific object. Let's try to clarify what a "definite object" and an "indefinite object" are!
Definite object / definite conjugation:
any object preceded by the definite article a or az (E.g., Hallod a dalt? - Do you hear the song? Keresi az ajtót - He is looking for the door. Nézik a szép tájat - They look at the beautiful landscape.)
that includes objects which have a demonstrative adjective in front of them, since these also include the definite article. (E.g., Ezt a kettőt ismerem - I know these two. Azt az almát kérem - I would like that apple.)
an object which is a proper noun (E.g., Jól ismerem Budapestet. - I know Budapest well.)
3rd person pronouns in the accusative (őt, őket) (E.g., Őt mindenki ismeri - Everybody knows him).
"Formal you" pronouns in the accusative (önt, önöket, magát, magukat)
demonstrative pronouns in the accusative (ezt, ezeket, azt, azokat)
Any of these pronouns may be omitted from a sentence with a verb in the definite conjugation if it can be inferred from context: Ismered a főnököt? Igen, ismerem. - Do you know the boss? Yes, I know [him]. It is not necessary to include őt in the second sentence.
- An object which is expressed by an entire clause: A főnök tudja, hogy új munkások jönnek - The boss knows that new workers are coming. The sentence could also be written using azt as an explicit object for the verb: A főnök azt tudja, hogy új munkások jönnek. The logic of the definite conjugation here is something like this: "The boss knows [the definite fact] that new workers are coming." Látom, hogy ég a házad - "I see [the definite fact] that your house is burning."
Indefinite object / indefinite conjugation:
Any object preceded by the indefinite article egy. (E.g., Egy kutyát látok - I see a dog)
An object not preceded by any article (excepting proper nouns) (E.g., Újságot olvas, he is reading a newspaper.)
The interrogative pronouns kit, kiket, mit, miket (E.g. Mit csináltok? - What are you doing? Kit szeret a lány? - Who does the girl like?)
1st and informal 2nd person pronouns (E.g. Ő szeret téged, de engem nem szeret.) These pronouns may be omitted if they can be inferred from context. A transitive verb in Hungarian which is in the indefinite form and seems to be missing an object may have engem or one of the others as its implied object; this can be a little confusing.
And indefinite conjugation, of course, when there is no object - neither in the sentence nor implied. (E.g. Tanulsz, vagy olvasol? - Are you studying or reading?)
Nem tudok főzni[, mert nincs tudásom hozzá]. ~ I can't cook[ because I have no knowledge of it].
Nem tudom AZT MEGfőzni[, mert nincs eszközöm hozzá]. ~ I can't cook it[ because i don't have the tools to do it].
Nem akarok főzni[, mert nincs kedvem hozzá]. ~ I don't want to cook[ because I don't feel like it].
Nem akarom AZT MEGfőzni[, mert nincs kedvem hozzá]. ~ I don't want to cook it[ because I don't feel like it].
Nem akarom AZT MOST MEGfőzni[, mert nincs most időm arra]. ~ I don't want to cook it now[ because I don't have time for it now].
A comment by JohnWeber786406 here: https://forum.duolingo.com/comment/16440466
"So......I need to investigate: definite vs. indefinite https://www.youtube.com/watch?v=iqQi8D1eJGU
- intransitive verbs (no object)
- no or indefinite article present
- quantity words
- indefinite pronouns
- 1st/2nd person pronouns
- interrogative pronouns
- relative pronouns
- definite articles
- proper name/third-person pronouns
- demonstrative pronouns (ez, ezek)
- reflexive pronouns
- entire clauses"
Also, peter.kristof's post: "Direct Object and Conjugation"