Top two items are popped from the stack and 'Greater Than' comparison is performed. 0 or 1 is pushed back to the stack where 1 indicates true.

See programming note for comparing unlike types

# Compares numbers to 50. 
# Pointless, in programming, but here to illustrate a point. 
100 50 gt 		# True, 100 is greater than 50 
45 50 gt 		# False, 45 is not greater than 50 
50 50 gt 		# False, 50 is not greater than 50

A B gt
#If A is bigger than B, TRUE
#Otherwise FALSE