Jiangyou - also known Sai-yau, Lak-yak, or Hak yau, as is the Mandarin name for a form of Soy sauce used in Singaporean cuisine and some Malaysian cuisine. It is a darker, thicker, sweeter sauce similar to the Chinese dark soy sauce - which makes sense considering the large influence Chinese culture has had in those countries.
Jiangyou should be kept sealed when not in use. Refrigeration is not necessary, but can help lengthen the life of a bottle. Do make sure to keep the sauce out of direct heat and light however, as these can drastically decrease the shelf life. Properly cared for bottles should last between 3 and 6 months.