Binomial count ($K\sim \mathrm{Bin}(n,p)$)

A binomial count $K$ records the number of successes in $n$ independent Bernoulli trials with common success probability $p$. It is the sum of the success indicator variables, so $K\sim \mathrm{Bin}(n,p)$, with expected value $np$ and variance $np(1-p)$. Ten independent coin flips give a binomial count of heads; ten dependent outcomes generally do not, even if each marginal success probability is $p$.