Lyle's Golden Syrup is made from evaporated sugar cane juice by
Tate & Lyle PLC ("A global leader in carbohydrate processing" according to their homepage). It is a
gloopy, golden-coloured transparent substance with a unique taste - a bit like sugar, but... darker, somehow.
It's supposed to be used as a sweetening ingredient when cooking or making sandwiches. However, it can be eaten neat, in which case it is helpful when dealing with emotional stress. It is extremely calorific, containing roughly 400k/cal per 100g.
Lyle's Golden Syrup is available in glass jars or, more traditionally, metal tins with pop-off lids. It's very common in the UK, but apparently quite obscure in the US.