Even though binomial trials only have 2 outcomes (yes/no, true/false, pass/fail, for/against), in large enough trials, they can be approximated with the normal distribution.

For example, say you want to roll a "6" with one 6-sided die.

Then there is a 1/6 chance of rolling a 6 and a 5/6 chance of NOT rolling a 6. This is a binomial experiment because there are only 2 outcomes: success or failure.

What is the probability of not rolling a 6 until the 4th roll?