Learn Spanish (Latin America): El perro está junto a mí.

In Spanish, after prepositions like a (to or at), para (for), and de (of or from), we have to use special prepositional pronouns. Instead of using the subject pronoun yo (I) or the object pronoun me (me), we use mí.

Why does mí have an accent mark here?

The accent mark is just there to tell it apart from the possessive word mi (my). You use mí with an accent when you mean 'me' after a preposition, like in junto a mí, and mi without an accent when you say things like mi perro (my dog).

Why use está instead of es?

We use está (from the verb estar) because the sentence is talking about physical location. To say where someone or something is located, we always use estar, never ser.

How does junto a work?

While junto often means 'together', the specific phrase junto a is a fixed expression meaning 'next to' or 'close to'. The preposition a is what connects the location phrase to the pronoun mí.