Interrogatives are also known as question words because they indicate that a sentence is a question.

You'll notice that they are almost exactly equivalent to the English interrogatives who, what, where, when, why, and how, except for the two words cuál and cuánto.

Cuál is translated as "which" in most contexts, but when a number is being asked about it translates to "what". For example, "cuál perro fue" is "which dog was it", but "cuál es tu numero?" is "what is your number?"

Cuánto is the general interrogative for quantities and translates as "how much", "how many", and similar phrases.

It's important to use the diacritical marks with interrogatives because their meaning changes subtly without them.

For instance cómo, which means "how", without the diacritical changes to como which means "like" or "as".

qué with the diacritical changes to que which is the adverb meaning "that" or "which".