You might have noticed that the phrases for greeting and parting ended in


, as with
The phrases when introducing oneself to people for the first time all end in



, as with
The 


form is used when meeting someone for the first time because it is considered
to be more formal than the


form. You need not worry about being
unintentionally rude when using an


form; it is informal but still
considered polite.
This topic of levels of politeness and formality is deeply knitted into the Korean language, and is covered in great detail in most Korean grammar books.