Learn Hardcore Croatian: Na poslu često koristim Internet, ali kod kuće radije čitam knjige. - At work I often use the Internet, but at home I prefer to read books.

The preposition na + locative is often used for “at (a place)” when that place is seen as an activity or an area where something happens, for example:

na poslu – at work
na fakultetu – at university
na koncertu – at a concert

The base form (nominative) is posao (“work, job”). With na in the sense of “at (a place)”, it changes to na poslu in the locative: Na poslu često koristim Internet = “At work I often use the Internet.”

Why is it kod kuće and not u kući for “at home”?

Kod kuće is the standard idiomatic way to say “at home” in Croatian. Literally it means “by/at the house.”

kod
- genitive (kuće, gen. of kuća) → “at someone’s place, at home”
u kući literally means “in the house (inside the building).”

So:

Danas sam kod kuće. – I’m at home today. (my place, not out)
Danas sam u kući. – I’m in the house (not outside in the yard / elsewhere).

In your sentence ali kod kuće radije čitam knjige, the idea is “but at home I prefer to read books,” so kod kuće is the natural choice.

Can the word order be changed? For example, can I say Često na poslu koristim Internet or Na poslu Internet često koristim?

Yes, Croatian word order is fairly flexible, but changes in order can change the focus or sound less natural.

All of these are grammatical, but differ slightly in emphasis:

Na poslu često koristim Internet. – Neutral: “At work I often use the Internet.”
Često na poslu koristim Internet. – Emphasizes how often this happens (“Often, at work, I use the Internet”).
Na poslu Internet često koristim. – Possible, but sounds more marked/poetic; extra emphasis on Internet (“At work, the Internet I often use”).

The most natural everyday version is the original: Na poslu često koristim Internet. Put adverbs like često (often) close to the verb or near the beginning for neutral style.

What exactly does radije mean, and how is it different from više volim?

Radije is the comparative form of the adverb rado (“gladly, willingly”).

rado – gladly
radije – more gladly / rather

So radije čitam knjige literally means “I read books more gladly,” which corresponds to English “I’d rather read books / I prefer reading books.”

Više volim means “I like more” or “I prefer,” built from više (more) + volim (I like/love):

Više volim čitati knjige. – I prefer to read books.
Kod kuće radije čitam knjige. – At home I rather/usually prefer to read books.

They are very close in meaning; radije is a bit shorter and more adverb‑like, while više volim explicitly mentions “liking” something more. Both are common and natural.

Why is radije placed before čitam? Can I say kod kuće čitam radije knjige?

The neutral position for sentence adverbs like radije is usually before the verb:

kod kuće radije čitam knjige – neutral and most natural.

Other orders are possible:

Kod kuće čitam radije knjige. – grammatical, but puts a bit more stress on radije and knjige as a group.
Kod kuće knjige radije čitam. – sounds more marked/emphatic or stylistic.

Everyday speech will almost always use something like Radije kod kuće čitam knjige or the original ali kod kuće radije čitam knjige. So yes, you can move it, but the original order is the most natural.

Why is there no word for “I” in the sentence? Where is the subject?

Croatian is a pro‑drop language: subject pronouns like ja (“I”) are normally omitted when the verb ending already shows the person.

koristim = I use
čitam = I read

So Na poslu često koristim Internet automatically means “At work I often use the Internet.”

You could say Ja na poslu često koristim Internet, but ja would add extra emphasis (something like “I often use the Internet at work,” maybe in contrast to others). In neutral statements, you usually leave ja out.

Why is there a comma before ali?

In Croatian, when ali (“but”) connects two full clauses (each with its own verb), you must put a comma before ali.

Your sentence has two clauses:

Na poslu često koristim Internet,
ali kod kuće radije čitam knjige.

Each has its own subject (implied ja) and verb (koristim, čitam), so they are independent clauses. Therefore, the comma before ali is required, just like in English: “I often use the Internet at work, but at home I prefer to read books.”

Why is knjige in the plural, and what form is it exactly? Could I say knjigu instead?

Knjige here is accusative plural, the form used for the direct object of the verb čitam (“I read”).

Nominative singular: knjiga – a book
Accusative singular: knjigu – (I read) a book
Accusative plural: knjige – (I read) books

In radije čitam knjige, the meaning is “I prefer to read books (in general, more than one, as a type of activity).”

If you say radije čitam knjigu, it sounds like “I would rather read the book / a book (one specific book),” usually in some specific context. So both forms are possible but they convey slightly different nuances.

Why doesn’t Internet change form here? Is it in some case, or is it indeclinable?

Internet is a masculine noun. In this sentence it is the direct object, so it is in the accusative singular.

For inanimate masculine nouns, the nominative and accusative singular often have the same form:

Nominative: Internet – the Internet (as a subject)
Accusative: koristim Internet – I use the Internet

In other cases it does change, for example:

Genitive: bez Interneta – without the Internet
Locative: na Internetu – on the Internet

So it’s not indeclinable; it just happens that the nominative and accusative look identical.

Why is Internet capitalized? Should it be internet with a small “i”?

Traditionally, Croatian treated Internet as a proper noun (like a specific global network), so it was often written with a capital I: Internet.

However, in modern usage, both Internet and internet appear, and many style guides now prefer the lowercase internet, especially when it’s seen as a common technology rather than a unique named entity.

So:

Na poslu često koristim Internet. – older/more formal style.
Na poslu često koristim internet. – modern, very common, and fully correct.

Both are understood; you won’t be misunderstood either way.

Why is the present tense used for something habitual? Could Croatian also use some other tense here?

The present tense in Croatian is used, just like the English simple present, for habits and regular activities:

Na poslu često koristim Internet. – I often use the Internet at work.
Kod kuće radije čitam knjige. – At home I prefer to read books.

You don’t need any extra words like “usually” or a special tense; the adverbs često (“often”) and radije (“rather/prefer”) plus the present tense clearly show a habitual action.

Other tenses (e.g. past, future) would change the time reference, not the “habitual” meaning. For example:

Na poslu sam često koristio Internet. – I often used the Internet at work. (in the past)

Would this sentence change if the speaker is a woman instead of a man?

No, this sentence would stay exactly the same for a male or female speaker.

In the present tense, verb endings do not change with gender:

koristim, čitam – “I use, I read” (same for men and women).

Gender appears in other forms (for example in the past tense or with adjectives):

Koristio sam Internet. – “I used the Internet.” (male speaker)
Koristila sam Internet. – “I used the Internet.” (female speaker)

But for the present tense sentence Na poslu često koristim Internet, ali kod kuće radije čitam knjige, there is no difference by gender.