Spanish accents

Spanish accents are important. More often than not, an accent (or lack of it) completely changes the meaning of a word. Understanding Spanish accent rules is therefore essential if you want to read and write Spanish effectively. If you understand Spanish accents, you will know how to pronounce words precisely, and you won’t be confused when you come across a written word with an accent.
An accent mark shows you exactly how a word is supposed to be pronounced, and often, it even shows you what that word means. It makes Spanish pronunciation and comprehension that much easier. Spanish uses three “accent marks” called diacritics: the diaeresis (ü), the acute accent (é), and the tilde (ñ).
The Acute Accent in Spanish
Spanish uses only the acute accent, over any of the five vowels: á, é, í, ó, and ú. At most, it appears once per word. This accent is used to mark the tonic (stressed) syllable, though it may also be used occasionally to distinguish homophones such as si (‘if’) and sí (‘yes’).
In contrast with English, Spanish has an official body that governs linguistic rules, orthography among them: the Royal Spanish Academy, which makes periodic changes to orthography. It is the policy of the Royal Spanish Academy that, when quoting older texts, one should update spelling to the current rules, except in discussions of the history of the Spanish language.
More often than not, an accent (or lack of it) completely changes the meaning of a word. Both words are pronounced the same. The accent only matters in writing.
Here some examples:

Grammar : Acentos españoles

Unaccented Spanish word	English	Accented Spanish Word	English
si	if	sí	yes
de	Of, from	dé	give (third-person singular present subjunctive)
el	the (masculine singular)	él	he
mas	but*	más	more
mi	my	mí	me (object pronoun)
se	(reflexive pronoun)	sé	I know
te	you (object pronoun)	té	tea
tu	your	tú	you