Registration If Statements?
 

Just wondering if something like this is possible just using things like if statements or if it is much more advanced. If so, are there threads I can look at to get started on it as I've searched with no real luck.

For example on the registration page if someone selects off the country list the United States a list of all the states would show up below it to select the state they live in. If they select Canada for their country a list of all the provinces would show up. I understand how to make all the lists but I would like it so depending what they select for country the proper drop down list will show up.

Hoping this is something that I can do or is fairly simple. Thanks in advance for any and all help!!