A proportion is the fraction of some total that is of a particular kind, either (i) as a count of one type of thing out of a total count, or (ii) as a component of a continuous variable.
A proportion is the fraction of some total that is of a particular kind.
The term 'proportion' will generally apply in either of two fairly common situations - (i) as a count out of a total count (the proportion of females in executive positions); and (ii) as a component of a continuous variable (such as the proportion of sugar by weight in a cake). The first is more common than the second.
The first is sometimes associated with binomial models, the second with beta models.
References:
Britannica - sample proportion
Wikipedia - compositional data
