A talent is the largest unit of weight used to measure gold or silver. The exact weight of a talent varied depending on time, location, and metal being measured, but was about 58-80 lbs. It is unlikely there was a single coin of that weight, so most likely it was a "bag of gold" (or silver), as the NIV renders the text. Because this is only a parable, the exact nature of the money is not important, so we can imagine it as a heavy bag of 600 ten-drachma silver coins. What IS important is that even a single talent was a huge sum of money, way more than even the 30 pieces of silver that Judas received when he betrayed Jesus. The NIV verse footnote states, "a talent was worth about 20 years of a day laborer's wage". So the servants had a lot of responsibility on their hands. The master distributed the money according to each servant's ability.