Learn Italian: Manifestare è un nostro diritto.

In Italian, when an action is the subject of a sentence, you must use the infinitive form of the verb. English often uses the '-ing' form (the gerund) for this, like 'demonstrating', but Italian never uses its gerund (like manifestando) as a noun.

Why does the sentence use un nostro diritto instead of il nostro diritto?

Both are grammatically correct, but they carry a slight difference in nuance. Using the indefinite article un makes it mean 'a right of ours' or 'one of our rights', implying it is among several rights we hold. If you used il nostro diritto, it would mean specifically 'our right'.

Is manifestare the normal word for attending a protest?

Yes! In political and social contexts, manifestare is the standard verb for demonstrating or protesting. You will also frequently see the related noun, una manifestazione, which means a demonstration or protest rally.

How could I use a causal conjunction from this lesson, like visto che, with this statement?

You can use this entire statement as the cause or reason for another action. For example: Visto che manifestare è un nostro diritto, andiamo in piazza (Seeing as demonstrating is our right, we are going to the square). Because visto che and dato che are flexible, they can easily sit at the very beginning of a combined sentence.