Salary and negotiation
In general, it's a lot easier to be picky about salary once you already have job experience. If this is your first job, and you can afford to not worry about how much make, I would recommend just taking what you're offered.
One thing to remember is cost of living. In some cities the cost of living is really high. I've heard stories of people working for startups in SF and making net negative money after paying rent.
If you have work experience and you're being offered less than you've made before, I would consider letting the company know that: "I'm really excited about your offer, but I just wanted to let you know that in the past I've been paid
Also, if you have another offer that's offering more money, you can let the other companies know that - sometimes they will match it!
When I ask for more money, I not to make it seem like it's a strong deciding factor for me (because it's not) but that it's just something I'm thinking about.
It's better to talk about salary on the phone (I know, phone calls suck - but this is how people do it and it'll probably give you the best chance. Write a script, it'll help)
How much is a dollar worth?
Some advice from Rudi:
The first time I was paid for work other than mowing the lawn for my parents, it was a mere 200$ for some contract work on the Internet. But wow, that felt like a lot of money. I could buy so many Magic The Gathering Cards!
The second time was a research internship in the summer. It was paid minimum wage, but it more than doubled my bank account which didn't contain much.
The third time was half of my current salary, but I managed 4 months worth of tuition! (Tuition is cheaper in Canada)
When you're a student and the most money you've made is from distributing newspapers, the first offer you get can seem like a money. If one company pays an extra 1$/hour more than the other, that's 500$ over a summer. It feels like a pretty big difference. Almost a full iPhone.
And maybe it is for you. Maybe you are struggling to pay off your living expenses and would like to support your family. Do what you need to do.
For everyone else, keep in mind that you are doing an internship to learn, not to get rich. This isn't about how evil money is and all that. It's just that given that you are only working 3-4 months, the difference between your offers will be quite negligible in the long run in most cases. On the other hand, doing to a place with better learning opportunities will often unlock more options for future internships and full-time employment, some of which will pay more. And at that point, the difference will start to be significant, because you'll be working at that place for years. So even if money really is your end goal, try to think about it over the long run.
Also, most humans are quite bad at predicting what will make them happy. This research on money and happiness has some good life advice.
As mentioned above, internships are more about learning than making money. That being said, if you still intend to negotiate, then there's a few things to keep in mind.
From the perspective of the company, there's a few reasons why they might not want to raise your offer: 1. They want to hire interns are cheaply as possible 2. They don't have the money 3. They can hire someone just as good as you for the same amount of money 4. They want all their interns to be paid the same to avoid resentment
You should try to figure out what constraints they have to use the most effective approach in negotiating.
It's difficult to do anything about (1) and (2). If you can demonstrate that you are significantly more productive, you might be able to make an economic argument that they'll get so much more work out of you that it's worth the slight increase in cost, but it will be hard.
Case (3) will often be true at well-known, competitive companies. If you don't have a truly extraordinary accomplishment, negotiating might not be seen well.
As a rule of thumb, if internship salary is publicly available for a company, (4) is likely to apply. You'll have a better chance of negotiating at smaller companies with fewer interns. Your negotiation is more likely to be successful if you can give them a story that would justify the salary disparity if other interns were to ever find out. This could include: "you have significantly more work experience", "you are senior", "you are a return intern". You can also try "my other offer/previous salary was higher" though that is less likely to work for internship than full-time positions, especially at larger companies that have dedicated internship programs.