Mike,
The birth control pill is a mixture of hormones that make a woman's body work differently.
Imagine you have a horrific toothache and your doctor gives you a medication to kill the pain. You are supposed to take it every four hours.
If you take it every fours hours your pain is pretty much gone. But you are really busy and forget to take it. So for the first hour you don't notice the pain much. But the second hour suddenly the pain is bad as all the medication is out of your body and nothing is killing the pain. You aren't near your medication so - so you have to wait til you get home and you have to wait 30 minutes. You take the medication, but it takes 30 minutes for it to work. So now you are in agonizing pain while you wait for it to work.
What do you do for your next pill? Take it the originial time you were supposed to take it? or four hours from when you took the late pill? Or do you try to skip a dose because the four hours are almost up.
Whatever you do impacts how much medication is in your body and how it kills the pain. And if you take it too soon it might just give a stomach in addition to the pain.
So a birth control pill is just like that - if you don't take it every day at the same time there will be hours when you are unprotected.
But a birth control pill is different, in that because you just take it once a day you do have a bit of a window. It works best if you take it at the same time - but if you vary by 1-2-3 hours you are OK. 4 is pushing it.
Also if you skip a day, it really takes 4 days ( to be on the safe side) for you have all the medication in your body you need to prevent pregnancy. If you skip two days - it takes 8 days. And if you skip 3 days- just consider yourself no longer protected from pregnancy until after the next menstrual period has started.
Birth control works best when taken at the same time every day on an empty stomach ( so for most people that means first thing in the morning.) Teenagers, whose hormones may be a bit irregular naturally - this goes for double!
Susan