back pain

i was doing sqauts at the gym and i was gradually increasing weight until i could only do about 3 reps and i noticed on the last set that my back started to hurt
is that normal

Okay- You're just getting started with working out- So yes, pain in general is to be expected. Back pain during squats is to be expected, since your back does get a workout when you squat- What you're doing wrong is lifting too heavy for your level of experience.
I know everyone wants to jump right in with both feet, but at this point in the game, your body isn't used to doing squats at all- So you want to stay light. In fact, you should stay light for EVERY exercise for a couple of months at least- Make sure you have the proper form before you start adding challenging amounts of weight. Hell, there are guys who've been doing this stuff for years who won't try three rep sets- Even when you have proper form, it can be very taxing, and dangerous. If I were you, I'd stick with a weight you can do 10-12 reps with for now, and then add weight for less reps later on- After you're sure you have good form.

i understand wat ur saying but does lifting less weight apply for when i am doing everything else because the only time that i feel pain is in the spaut
thanks

Yes, lifting less weight applies to everything- The fact that you feel pain isn't the issue really- The fact that you're pushing your body this hard when you're just starting out is. So, regardless of whether you feel pain or not, stay light for a little while. By light, like I said earlier, I mean use weights that are challenging in the ten to twelve rep range, don't just use really light weights and do ten to twelve reps. It's still a beneficial rep range for building muscle anyway, and it's a hell of a lot safer than trying to jump into heavy weights and low reps right from the start. Your body really, really, really has to get used to the proper movement. Just imagine this- You're new to lifting, and you're excited, so you want to lift as much as possible. You try to squat heavy weight, and get yourself a hernia for Xmas- A bad one. Now you need serious surgery, which means you can't lift ANYTHING for quite some time- And you have SERIOUS pain. Chances are, you might never return to the weights- And if you do, at best, it'll be very frustrating and sorta scary for you- And your body still isn't aware of the proper form at this point. Remember, proper form isn't just about reading how to do the exercise and then trying your best- It's another case of practice makes perfect, and the smart way to practice is with a lesser amount of weight, so there's less chance of you tearing something important. Let's say your max squat weight at this point, for three reps, is 250 pounds- (Just a number, not saying this is how much you should be lifting or anything like that.) If you try to get used to proper form at this weight, and you become a little unbalanced at some point- Your muscles will be pushed to their limits to try and re-balance themselves, and could get injured. Or, you could overcompensate when trying to re-balance, and have the same thing happen. Now, let's say instead that you decide to learn proper form with a lighter weight- You find yourself challenged in the ten rep range with 180 pounds. If you become unbalanced under that, your muscles should be able to handle it a lot easier. Before you know it, you're more balanced as your body gets used to the movement, and you feel comfortable enough with your form to add more weight- Even at this point, don't go overboard. Be smart about how much more weight you pile on that bar. Squats are just an example here, the same reason applies to every one of your exercises. If possible, have someone check your form for you- Someone who has an idea of what the proper form is supposed to be.
Remember, patience plays a huge part in success when it comes to lifting- It sucks, everyone wants results and big weights as fast as possible, but going too hard too fast is asking for serious trouble. No one wants to be the crippled guy with a gut who talks about how he "used to" lift heavy weights as though it somehow earns him respect- The only people worth respecting are those who not only work hard, but also work smart and treat their bodies well. If you beat your body up, sooner or later it's going to hit back- Hard.

Edit- To clearly answer your actual question regarding pain- It's perfectly normal to feel some back pain from squats, especially if you're just starting out. Since you went heavy, you can probably expect the pain to stay a while, perhaps even if you didn't damage anything- You probably might need to lay off lifting until the pain is gone, by the way- The lower back is used to some degree in many, many exercises for many muscle groups, and you might notice that it bothers you even when you think it shouldn't. (i.e. Why the hell does it hurt when I'm bench pressing?) Don't try to lift through the pain- It's probably the dumbest move anyone can make. If the pain lasts more than a week and doesn't seem to be getting any better, go see a doc- You may have messed something up- I'm seriously keeping my fingers crossed for you, and I hope all this info helps.

thanks alot i really apreciate it