This is a characteristic of paper. It is defined as the mass of paper per surface unit (g/m2). Most of the physical characteristics of paper are closely and proportionally related to the grammage. Euro banknotes have a similar grammage to the previous national banknotes.
A curved pattern of fine, unbroken lines, difficult to reproduce.
Gresham, Sir Thomas. English financier (London, 1519-1579). Founder of the London Stock Exchange, he is also attributed the formulation of the law that bears his name, whereby in a monetary system formed by currencies of differing values, the least appreciated currency drives out that of higher value.