A continuous data set is where you can plot every point (even very, very small decimal numbers) because the unit can be measured in parts of the whole.
A discrete data set is where you can only plot the units in whole values. For example, if you were plotting the number of people, you can't have a part of a person.
Weight is measured in lbs which can be measured in parts of the lb (such as 100.005 lbs) so it is continuous.
