Why does 'elsif' have to come before an 'else' statement? Thanks

you are creating a set of mutually exclusive routes for your program logic to follow, meaning when an if block is entered, there is only one way out. the code is executing from top to bottom, so the first acceptable way out will be taken. so if your program logic is sorting numbers for example, and the current number is 500, and you have bins of less than 20, 20-70, or greater than 70, the first test (if) would be: is the number less than 20? 500 > 20, so no, next, or else if number 70 or less? no also, next, or else, meaning, the number isn't any previous choice, greater than 70. it's the default choice if nothing previous was taken.