Learn Hardcore Indonesian: Poster itu dibuat untuk festival tahunan di kota kami. - That poster was made for the annual festival in our city.

membuat = to make (active voice)
- Kami membuat poster itu. = We made that poster.
dibuat = is/was made (passive voice)
- Poster itu dibuat (oleh kami). = That poster was made (by us).

In Indonesian, the passive is very common, especially when:

you want to emphasize the object (poster itu), or
the doer (the maker) is unknown, unimportant, or obvious from context.

So the sentence focuses on the poster itself, not on who made it.

How do I know dibuat means was made (past) and not is made (present)?

Indonesian verbs do not change form for past, present, or future. Dibuat just means made; the time is understood from context.

If you really want to show past explicitly, you can add sudah:

Poster itu sudah dibuat untuk festival tahunan di kota kami.
= The poster has already been made / was made for the annual festival in our city.

Without sudah, context (e.g., when you say the sentence, or other sentences around it) tells the listener whether it’s past, present, or future.

Can I say who made the poster in this sentence? Where do I put it?

Yes. In a passive sentence with dibuat, you can add the agent after oleh:

Poster itu dibuat oleh kami untuk festival tahunan di kota kami.
= The poster was made by us for the annual festival in our city.

Other examples:

Poster itu dibuat oleh panitia. = The poster was made by the committee.
Poster itu dibuat oleh siswa-siswa. = The poster was made by the students.

The structure is:

[object] + [passive verb] + oleh + [doer] + ...

What exactly does itu mean in poster itu, and why is it after the noun?

Itu is a demonstrative meaning that or the (depending on context). It comes after the noun:

poster itu = that poster / the poster
kota itu = that city / the city

Indonesian pattern:

noun + itu (that/the)
noun + ini (this/the)

Without itu, poster is more like a poster or posters in general:

Poster dibuat untuk festival...
= Posters are (being) made for the festival… / A poster is made for the festival…

With itu, you’re clearly talking about a specific poster already known to both speakers.

Could I say Itu poster dibuat... instead of Poster itu dibuat...?

Itu poster dibuat... is not natural in standard Indonesian for this meaning.

Poster itu dibuat... = natural, means That/The poster was made...
Itu poster... usually would need a different continuation, like:
- Itu poster, ya? = That’s a poster, right?

So for that/the poster was made..., you should keep itu after poster:

Poster itu dibuat... ✅

What does untuk mean here, and can I replace it with another word?

Untuk means for (showing purpose or goal):

dibuat untuk festival tahunan = was made for the annual festival.

Near-synonyms and their nuance:

untuk – neutral, very common, for purpose
guna – more formal/literary, also for the purpose of
bagi – often for (the benefit of) someone, less common for events like a festival

You could say dibuat guna festival tahunan, but untuk is the most natural and common in everyday use here.

Why is it festival tahunan and not tahunan festival?

In Indonesian, adjectives and descriptive words usually come after the noun:

festival tahunan = annual festival
rumah besar = big house
kota kecil = small city

So:

festival = festival
tahunan = annual, yearly
festival tahunan = a festival that happens every year.

Tahunan festival would be incorrect in this context.

What is the difference between tahunan and setiap tahun?

Both relate to every year, but they are used differently:

tahunan is an adjective: annual, yearly
- festival tahunan = an annual festival
setiap tahun is a phrase: every year
- Festival itu diadakan setiap tahun. = The festival is held every year.

You normally say:

festival tahunan (not festival setiap tahun)
but diadakan setiap tahun (not usually diadakan tahunan).

Why is it di kota kami and not something like pada kota kami or ke kota kami?

Di indicates location (in, at, on), so di kota kami means in our city:

di kota kami = in our city
di rumah = at home / in the house
di sekolah = at school

Comparison:

ke = to (movement toward a place)
- Saya pergi ke kota kami. = I go to our city.
pada = at/on/in (more abstract, often with time or formal contexts)
- pada hari Senin = on Monday
- pada kesempatan ini = on this occasion

For simple physical location, di is the normal choice, so di kota kami is correct and natural.

What is the difference between kami and kita in kota kami?

Both mean we / us / our, but:

kami = we (excluding the person you’re talking to)
- kota kami = our city (but not including you, the listener)
kita = we (including the person you’re talking to)
- kota kita = our city (including you, the listener)

So:

di kota kami suggests it’s the speaker’s city, but not the listener’s.
di kota kita would be used if the listener also lives in that city.

Is poster here singular or plural? How do I know?

Indonesian nouns usually do not change form for singular vs plural. Poster can mean poster or posters, depending on context.

Poster itu strongly suggests that poster / the poster (singular, one specific poster).
If you wanted to be clearly plural, you could say:
- poster-poster itu = those posters (plural, more than one)
- or add a number: tiga poster = three posters

In your sentence, Poster itu dibuat... is most naturally understood as That poster was made... (singular).