Basic rules: -Palabras esdrújulas (stress on the third-to-last syllable or before): always accent -Palabras llanas (stress on the penultimate syllable): accent only when the word does NOT end in vowel, s or n. -Palabras agudas (stress on the last syllable): accent only when the word DOES end in vowel, s or n. -Words with only one syllable do NOT have accent. Examples: Esdrújulas: teléfono, número, triángulo, micrófono. Llanas: cáncer, débil, tijera, joven, antes. Agudas: café, educación, París, final, matar. Simple, right? Well, there are other rules and exceptions which makes the topic way more complex. For example: -Words where the diphthong has to be broken have accent (día, frío, panadería) -Words with only one syllable but with two meanings that can be confused may have the accent to distinguish then from one another. For example: te (pronoun) and té (drink). -Adverbs in -mente have the same accent as the original adjective, no matter the number of syllables when "-mente" is added. For example: difícilmente BUT cariñosamente. There must be other rules that I can't come up with right now :P

Yes, there are.

Sorry, but not a very good explanation by some of the other guys. Word ending in vowel, n, or s: stress on penultimate syllable. (comIda) Word ending in anything else: stress on last syllable. (comeR) Any word with accent mark: first two rules don't apply and put stress on syllable with accent mark. (carámbano)