semua

1. Position in a Sentence
A common position for semua is before the noun: semua murid (all students). However, it can also 'float' after a pronoun for emphasis: Mereka semua (They all).

2. Plurality and Reduplication
In Indonesian, noun reduplication is used to show plurality. However, because semua supplies the quantity, a bare, number-neutral noun is sufficient in the ordinary pattern. Saying semua buku-buku is often edited to semua buku in concise formal prose. This does not prohibit reduplicated lexical nouns or every contextual use of reduplication.

3. Standalone Use
Semuanya can mean all of it, all of them, or everything when the referent is understood. Bare semua also works independently, as in Semua sudah siap (All are ready); -nya is not compulsory whenever the following noun is omitted.

4. Comparison with Segala and Seluruh
Semua commonly quantifies a relevant set or amount. Segala often emphasizes all kinds or everything in scope, and seluruh often emphasizes a whole, as in seluruh dunia. These words overlap: seluruh siswa can also mean all the students. They are not rigidly divided into countable, abstract, and single-entity meanings.

5. Formal Address with Sekalian
In formal settings, you might hear sekalian used after a noun or pronoun to mean 'all of you' or 'everyone', such as Teman-teman sekalian (All friends/Everyone).

Choosing the Intended Scope: Seluruh dunia is a clear model for the whole world. Semua dunia could have a different interpretation, such as all worlds in a fictional setting. The choice concerns the intended set or whole, not an absolute grammar ban.