Learn Hardcore Esperanto: Hodiaŭ la retejo denove funkcias, do mi povas aĉeti bileton per la interreto. - Today the website works again, so I can buy a ticket via the internet.

la retejo = the website (a specific site that has been down and now works again).
- Morphology: ret- (net/web) + -ej- (place) + -o (noun) → “place of the web”.
la interreto = the internet (the whole global network / the medium you use).

So the sentence literally says:
“Today the website works again, so I can buy a ticket via the internet.”

You use retejo for a particular site, and interreto for the whole system/medium.

Why is there la before both retejo and interreto?

In Esperanto, you usually use la when you are talking about:

A specific, known thing:
- la retejo = that particular website (for example, the ticket‑selling site).
A unique, well‑known thing (like “the sun”, “the earth”, or a unique system):
- la interreto = the (one) internet.

Both are definite here, so la is used:

la retejo (the specific site I need)
la interreto (the familiar global Internet everyone knows)

Could I say “Hodiaŭ la retejo denove funkcias” in a different word order, like in English?

Yes. Esperanto word order is fairly flexible. All of these are grammatically correct and natural:

Hodiaŭ la retejo denove funkcias.
La retejo denove funkcias hodiaŭ.
La retejo hodiaŭ denove funkcias.

Placing hodiaŭ at the beginning emphasizes today a little more, like:
“Today, the website is working again…”

The basic meaning does not change; it’s mostly a matter of emphasis and style.

Why is it denove funkcias and not something like estas denove funkcianta?

Both forms are possible, but they differ in style:

denove funkcias = “works again / is working again”
- Simple, direct, and the most natural in Esperanto.
estas denove funkcianta = “is again functioning” (present progressive)
- Grammatically correct but heavier and usually unnecessary.

Esperanto normally avoids complicated verbal constructions if a simple verb form exists.
So funkcias is preferred over estas funkcianta in most cases.

Why is the verb funkcias in the present tense (-as) when we say “Today the website works again”?

Esperanto present tense -as is used for actions or states:

happening right now
that are true in the present period (e.g. “today”)

So Hodiaŭ la retejo denove funkcias means:

“Today (in the present time) the website is working again.”

If you used funkcios (future), it would mean “will work”, referring to a future time, not now. Since we’re talking about the situation today, funkcias is correct.

Why is it mi povas aĉeti and not mi povas aĉetas?

Verbs like povi (“can, to be able to”) work like modal verbs in English. The pattern is:

mi povas
- aĉeti (infinitive) = I can buy

In Esperanto:

povas → can (finite verb, conjugated)
aĉeti → to buy (infinitive, unchanged after a modal verb)

You never conjugate both verbs. You say:

mi volas dormi – I want to sleep
mi devas iri – I must go
mi povas aĉeti – I can buy

*mi povas aĉetas is ungrammatical.

Why does bileton have -n at the end?

The -n ending marks the accusative case in Esperanto, usually the direct object of the verb.
Ask: “Buy what?” → “a ticket.”

mi (subject, no -n)
aĉeti (verb, infinitive)
bileton (direct object, what is being bought)

So:

Mi aĉetas bileton. = I am buying a ticket.
Mi volas bileton. = I want a ticket.

Without -n, bileto would look like a subject, which would confuse the grammar. The -n clearly shows it is the object.

Why is it per la interreto and not something like en la interreto?

The preposition per means “by means of / using / via”.
So per la interreto literally means “by means of the internet” → “online, via the internet”.

aĉeti bileton per la interreto
= buy a ticket using the internet.

en la interreto would be more literally “in the internet”, emphasizing location, not the medium used. For expressing the means or channel, per is the natural choice.

Could I say “Mi povas aĉeti bileton rete” instead of “per la interreto”?

Yes. rete is an adverb meaning “online, via the web” and is very common in modern Esperanto.

Mi povas aĉeti bileton rete.
= I can buy a ticket online.

per la interreto is a bit more explicit and literal: “by means of the internet”.
rete is shorter and sounds very natural in everyday usage.

What is the role of do in this sentence, and how is it different from ĉar?

do means “so / therefore / then” and introduces a result or conclusion:

Hodiaŭ la retejo denove funkcias, do mi povas aĉeti bileton…
= Today the website works again, so I can buy a ticket…

ĉar means “because” and introduces a reason:

Mi povas aĉeti bileton, ĉar la retejo denove funkcias.
= I can buy a ticket because the website works again.

So:

do → “therefore, as a result”
ĉar → “because, since (cause)”

They relate the same facts but from opposite directions (cause vs. result).

Is the comma before do necessary?

Stylistically, it is very common and recommended to put a comma before do when it connects two clauses:

Hodiaŭ la retejo denove funkcias, do mi povas aĉeti bileton…

The comma marks the boundary between:

Hodiaŭ la retejo denove funkcias
mi povas aĉeti bileton per la interreto

While Esperanto punctuation is somewhat flexible, using the comma here makes the sentence clearer and aligns with standard written practice.

Could I omit la and just say “per interreto” or capitalize “Interreto”?

Yes, there are a few stylistic options:

per la interreto – very common, treating the internet like “the sun”, “the world” etc.
per Interreto – capitalized, treating Interreto as a proper name (like “via Internet”). Then la is often dropped.
per interreto (without la, not capitalized) – also seen, but less standard; some speakers use it when they treat interreto more like a mass noun.

In your sentence, per la interreto is fully correct, clear, and neutral.