It is used:

- To mark the exceptions to the Rule of Stress.

- To distinguish between two meanings of the same word:

 El (the)- Él (he) 
 De (of) - Que él dé (that he may give)  
 Más (more)- Mas (but)
 Se (3rd person reflexive pronoun, "himself")- Yo sé (I know)

- In the following words established by use, as "ó" or "ú" (or),
"é" (and), "á" (to).

- In some words when used interrogatively, as Quién? (who?), Qué?
(what?), Cuál? (which?), Cúyo? (whose?), Dónde? (where?).

- On "I" and "U" when they occur together with "A", "E" or "O", the "I"
or "U" not belonging to the same syllable, viz., not forming diphthong
with "A," "E" or "O", as Filosofía (philosophy), El continúa (he
continues).

- On "I" following "U" when the "I" does not form a diphthong, but
stands as a separate syllable, as Concluído (concluded), Imbuído
(imbued).

- On Éste (this), Ése and Aquél (that) when these words are stressed.

The diaeresis is placed over "u" in "güe" and "güi" when the "u" is to
be sounded.

The tilde (~) is used on the letter "N" to turn it into "Ñ," as Mañana
(morning) (in old Spanish spelled Mannana).

These are used in Spanish both at the beginning and at the end of the
question or exclamation, as ¿Qué quiere V.? (what do you want?),
¡Cuántos sufrimientos! (how much suffering!). Note that at the beginning
they are reversed.

The other signs of punctuation are used as in English.

Capital letters are used as in English with the following exceptions:

- Adjectives of nationality are written with small letters, as Un
libro inglés (an English book).

- Days of the week generally (and sometimes the months of the year)
are written with small letters.