Didn't read the other responses so sorry if this is a repeat.
The polls are done by taking US Census information. So say for New Hampshire there are 900,000 people. (That's just a random number btw).
They take the sample size of the population, which involves a statistical formula with a 95% confidence level. You'd think the more people in a state the larger the sample size, but that's not the case. It's called the law of diminishing returns and you can look it up if you are interested.
So say a sample size for 900,000 is 700. They poll 900 people (the good polls anyway) by using a computer to randomly pick telephone numbers of people in the state.
The questions are asked by a professional sounding voice.
Most polls have a formula for determining "likely voters." They can be different for each poll. Remember not everyone votes.
So in the end of the 900 they get 800 or 700 but it has to meet the sample size formula for that state.
Here this says it better...http://www.surveyusa.com/client/methodology4.aspx
There is a method to the madness, however you have to remember the last two presidential elections, the polls were wrong. So if ya ask me, especially after studying ad nausea the last couple months, statistics and polls are a waste of time and money. The only reason these expensive polls are so popular is because the media wants them.
I think of it as wanting to jump into a lake you've never been in before. You're pretty sure what will happen, the size of the fish you'll encounter, the temperature of the water, the feel of the bottom, is it sand or mud squishing between your toes, but just for the added benefit of knowing you send three people down to the water before you to check and give you their opinion.
They come back and one or more will confirm what you thought already, and maybe one or more will tell you something you didn't know, but in the end, until you get in the water and find out for yourself, you'll never know what's real and what's just talk. And that's all polls essentially are, talk.
Many a slip twixt the cup and the lip.