N는, N은

1. The grammar used to express the subject of a sentence and it is used after the noun.

2. A noun without a Batchim is followed by a combination of '는'.

   저는, 나는 ( I )

   너는 (you) 

   그는 (he)

   영수는 (Young soo)

   중기는 (Joong gi)

3. A noun with a Batchim is followed by a combination of '은'.

   그들은 (They)

   지영은 (Ji Young)

   시진은 (Shi Jin)