1. GUSTAR is pleasing TO me!
In Spanish, we use the verb GUSTAR to say that we like something, but we are really saying that something is pleasing to us.

2. In English, we say: I like chocolate.
SUBJECT VERB OBJECT
I am the subject of the sentence because I am the one who LIKES the chocolate.
Chocolate is the object of the sentence because it is being liked. It receives the action of the verb.

3. In Spanish, we say: Me gusta chocolate
INDIRECT OBJECT VERB SUBJECT
In this sentence, subject and verb are reversed. Chocolate is the subject because chocolate is what IS PLEASING.
“Me” is the indirect object because chocolate is pleasing TO me.
In Spanish the person being pleased is NOT the subject of the sentence. Therefore the number of the verb (gusta vs gustan) is decided by what is pleasing, in this case chocolate.

4. Indirect Objects me = a mí = to me te = a ti = to you
le = a él, a ella, a usted, a (name) = to him, to her, to you (formal), to (name)
nos = a nosotros = to us
os = a vosotros = to you all (informal in Spain)
les = a ellos, a ellas, a ustedes, a (names) = to them (m), to them (f), to you all, to (names)

5. GUSTAR followed by a verb:
Gustar can also be used with a verb to say that you like to do something (to do something is pleasing to you).
When gustar is followed by a verb, or even more than one verb, it will always appear in the singular form (gusta).
The second (and any other verb) verb is left in its infinitive form (to do, to play, to talk)

6. ¿A quién le gusta…? ¿A quién le gusta practicar deportes?
Me gusta practicar fútbol.
¿Te gusta hablar con amigos?
A mi madre le gusta leer.

7.  Note: A Hugo le gustan películas de aventura.
When you use gustar with an indirect object pronoun (me, te, le, etc.) you can also include the indirect object (a nosotros, a Ana) to emphasize or clarify who is being pleased.
If you do so though, you must use the word “a”.

8. Conclusion – part 1
When using the verb gustar, you will only be using the third person singular and plural forms.
The number of the verb is determined by what is liked, not by who likes it.
Think of it as meaning “to please/to be pleasing to” rather than “to like”.

9. Conclusion - part 2
You must use an indirect object pronoun (me, te, le, nos, os, les) with gusta/gustan.
It is not optional; it is mandatory!
If you use a phrase like “A Juan” or “A ti” for emphasis or clarification, it is correct, but not obligatory.

10. Verbs like ‘GUSTAR’
aburrir -to bore fascinar- to be fascinating to importar -to be important to caer bien (mal)-to (not) suit chocar – to annoy (can’t stand) interesar-to be interesting to dar asco-to be loathsome molestar-to be a bother disgustar-to upset parecer-to appear to be doler (o:ue)-to be painful encantar-to love something quedar-to be left over, remain faltar-to be lacking something volver (o:ue) loco-to be crazy about