If statements are just that. They say, "If a is true, then do the following, if not, do this instead"
Here's a simple program for you that tests if someone is an adult.
var age : nat %Can't have negative age get age if age < 18 then put "You are not an adult!" else put "You are an adult!" end if
This program is saying: "Ask the user for their age. If it's under 18, then they're not an adult. If it's not under 18, then they are. Note that else statements do not check if they are greater/equal to 18, they just check if they are not under 18. This will suffice for our purposes
But what if we want to test for seniors too? This can be accomplished with an
... if age < 18 then put "You are not an adult!" elsif age > 64 then put "You are a senior!" else put "You are an adult!" end if
This is saying "If they are under 18, they're not an adult. If they're not under 18, then check if they're older than 64; if so, they are a senior. If neither of the above cases are true, then they are an adult.
Cases are like funny if-statements. They're pretty easy to understand, but you probably won't use them until later. Still, they fall under the same category as if statements, so you might as well get used to them now.