Salvadoran Castilian or Salvadoran Spanish is geographically defined as the form of Spanish spoken in the country of El Salvador in Central America. El Salvador is the only country in North and Central America to use the term Castellano or Castilian as oppose to Spanish or Español. The Castilian dialect in El Salvador shares many similarities to that of its neighbors in the region, but it has its stark differences in pronunciation and usage. El Salvador, like most of Central America, uses voseo Spanish as its written and spoken form, similar to that of Argentina. Vos is used, but many Salvadorans understand tuteo. Vos can be heard in television programs and can be seen in written form in publications. Usted is used as a show of respect, when someone is speaking to an elderly person.
Second person singular pronouns 
"Vos" is the dominant second person singular pronoun used by many speakers in familiar or informal contexts. Voseo is most commonly used among people in the same age group in addressing one another. It is common to hear young children address each other with "vos." The phenomenon also occurs among adults who address one another in familiar or informal contexts. "Vos" is also used by adults in addressing children or juveniles. However, the relationship does not re-occur when children address adults. Children address adults with "usted;" regardless of age, status or context.
Conjugations with the Vos Pronoun 
The conjugations with the vos second person form vary in comparison with its tuteo counterpart.
Affirmative Imperative 
The use of the imperative in Salvadoran Spanish is emphatic, with particular emphasis on the final letter of a given verb. The emphasis also removes the need for additional words that establish a given command. For example, ¡Ven aca! or ¡Ven aquí! becomes ¡Vení!
"Usted" is the formal second person singular pronoun in Salvadoran Castilian. "Usted" is used in addressing foreigners formally, for acquaintances, and in business settings. Unlike nearby Costa Rica, "usted" is not the dominant second person pronoun for addressing a person.
"Tú" is hardly used; the use of tú is limited strictly to foreigners. It is used in addressing foreigners familiarly and when writing correspondence to foreigners (again in familiar contexts).