When is "se" used before a verb?

Question

I'm confused about when "se" should be used. I thought it would always go before a like here:

Ella se mejora a su coche

but I see here that it is not being used.

Él observa a su hija

My question is, when is se used before the verb?

Answer 1

Emilio's links are correct.

I will focus on the wide use of se as reflexive.

Se can be translated as the third person pronoun, like the reflexive pronouns himself, herself, itself, themselves.

1. Él/Ella se mejora su coche --> He/She improved his/her car himself/herself

2. ¡La mesa se mueve sola! ¡Es magia! --> The table moves itself! It's magic!

3. Se alimentaron en el restaurante --> They fed themselves at the restaurant

In your first example you can drop the reflexive pronoun and everybody will understand you, it is just extra information.

In the second example you mention:

Él observa a su hija --> He watches her daughter.

You are asking about Él se observa a su hija

Se is indirect of the person who is doing the action (Él).

Él se observa a su hija --> He watches by himself to her daughter / He watches her daughter (by) himself.

I am not English but it sounds a bit strange to add himself here. In English I remember you can use himself / by himself / for himself but here it is useless. You can apply the same thing to Spanish.

I think I won't be wrong if I ask you to put in these sentences the pronoun themselves.

Las enfermeras están vigilando a los chicos --> The nurses are watching the children.

1. Las enfermeras se están vigilando a los chicos (not correct) -->The nurses themselves are watching the children (Watching includes the nurses on the action, you do not need the pronoun)

2. Las enfermeras están vigilando a los chicos por sí mismas --> The nurses are watching the children by themselves. (Correct... but they are nurses everybody knows the children will be ok, they are capable of, do you really need it on both sentences? )

Se has several uses, if you are learning Spanish in the future the other uses of se will become familiar to you but right now as a starting point I think it is enough to know its use as reflexive pronoun, it is quite usual.

For other uses you can use this website http://spanish.about.com/

Se venden oro y plata, although translated literally would mean "gold and silver sell themselves," can be understood to mean "gold and silver are sold" or even "gold and silver for sale," neither of which specify who is doing the selling. Se sirve desayuno means "breakfast is served." And se alquila, which might be seen as a sign on a building or object, means simply "for rent."

I am learning English so this answer can contain errors when it comes about translations and different uses of pronouns in English examples

Answer 2

SE Reflexivo.

El reflexivo significa que la misma persona que hace la acción la recibe.

suicidarse, especializarse, arrepentirse de, asombrarse de, atreverse a, burlarse de, darse cuenta de, empeñarse en, enterarse de equivocarse, portarse bien / mal, resignarse, quejarse

Hay otros que conocemos como reflexivos pero también pueden ser transitivos, es decir pasar su acción a otra cosa o persona.

Cambiarse, vestirse, lavarse, cepillarse

Me cambio todos los días y cambio mi dinero en el banco.

Aburrirse, alegrarse, cansarse, enojarse, divertirse, molestarse, preocuparse, interesarse, sorprenderse, asustarse, entristecerse, enfermarse, hincharse, mejorarse, curarse, pararse, sentarse, acostarse, etc.

También están los que nos indican un consumo total de algo.

Tomarse, comerse, beberse, devorarse.

Reflexive verbs are, in my opinion, the easiest se to grasp. Translated to English, a sentence with a reflexive verb will have the word self in there somewhere, and if not, the sentence will indeed express some kind of emotion. In English, we say that we want to Take a bath/shower when in Spanish you would bathe or shower yourself... or someone else even. Quiero ducharme -- I want to take a shower.

At the bottom of the list above are some other reflexives that do not express emotion, but rather, consumption of some kind, whether it be yourself or something else, a consumption of ... all of it... as the quote says.

nos indican un consumo total de algo

Example..

• We're eating all of the pizza / Nos comemos la pizza
• He drank the whole thing! / ¡Él se lo tomó!.

SE Recíproco.

Implica una acción y dos personas realizándola al mismo tiempo.( Ellos= se).

amarse, quererse, llamarse, verse, besarse, abrazarse, admirarse, tocarse, odiarse

I would call this the opposite of a Reflexive verb. These are personal verbs that involve another subject, as the definition suggests.

SE Accidental.

Se usa para expresar la realización de una acción de manera accidental o donde el sujeto no quiere asumir la responsabilidad.

Romperse, perderse, olvidarse, caerse, quemarse, doblarse, quebrarse, abrirse , descomponerse

In the Spanish language, for some reason, they do not accept the blame. You don't forget your wallet, your wallet forgets you. It's strange, but it's true.

SE Impersonal.

Lo usamos cuando no sabemos o no queremos o no importa quien hace la acción, sirve para expresar generalizaciones. Comúnmente aparece en la tercera persona singular con verbos intransitivos sin embargo también aparecen con algunos transitivos que se toman como “impersonales”.

Intransitivo. Se vive bien en Querétaro 
Transitivo. Se habla español en México.

You will often hear this usage when you are asked how to say something.

¿Cómo se dice ... potato... en español?`

Using English as an example you can see the trend used in this form of SE.

In English, we use "they" or "you" a lot to explain instructions, or advertisements, or, mainly, just to generalize... in some cases, "we"... as in We sell furniture... translated to Se vende muebles.

Other English examples -- in spanish.

We speak Spanish (like the signs outside of a business)

Se habla español

You open it with a fork (instructions)

Se la abre con tenedor

They say the homework is hard (generalize)

Se dice es dificil la tarea

You don't say it like that (instructions)

No se lo dice así

This impersonal "se" is a bit tricky to get used to. I still use it incorrectly to this day, even after 15+ years of practice and education.

Taken from my Advanced Spanish Manual, written by Veronica Martinez of ITESM Querétaro.

Answer 3

Just wanted to add some additional examples to maybe help clear your confusion of when to use se or when not to use, coming from a native speaker.

As others have already mentioned, the main use of "se" is reflexive. Compare/contrast the meaning of the following examples:

• Él se da la vuelta. vs Él da la vuelta.
• Ella se mira en el espejo/la televisión/etc. vs Ella mira el espejo/la televisión/etc.
• Él se avienta a la alberca. vs Él avienta la pelota.

A more complicated example could be something that is inherently reflexive, like

• Él se come la pizza. vs Él come la pizza.,

but I would argue that the fact these two statements express is the same, perhaps with only a slight change in emphasis. I hope these examples helped clear some of your confusion up.