People offer see salary negotiations as an antagonistic confrontation — you want to make as much as possible, they want to pay you as little as possible, and you have to battle it out to see who wins. But this is absolutely not the way that a salary negotiation has to work, or even should work.
Job searching is often compared to dating, so let's use a common example of negotiating within a relationship: where to spend a holiday. You want to spend it with your family, and your significant other wants to spend it with their family.
If you approach this as a battle, wherein you "win" if you spend the holiday with your family and "lose" if you spend the holiday with their family, then even if you "win," you may damage the foundation of your relationship. Similarly, if you approach a salary negotiation with an eye on dragging as much as possible out of the hiring manager, you may either come to a stalemate, where you walk away without a job, or you may so damage the relationship that you hurt your chances for future promotions and raises.
In most relationships, however, people are committed to finding a solution that seems fair to both of them. In our example, this might mean spending this holiday with your family and another holiday with their family, or spending it with their family this year and yours next year. There may be other factors to discuss and consider, such as the time and expense of travel, a special occasion taking place around the same time, or the chance to see a sibling who is coming home from abroad.
In this case, nobody gets 100% of what they want 100% of the time, but they both feel that they've reached a fair solution that honors both their wants and needs.
This is the approach that you want to take with salary negotiations. You and the employer both have different priorities: They want to hire someone with your skills and expertise, but they don't want to go over their budget to do so. You want the security and benefits of working in this job, but you want to make sure that you're being paid a fair amount for the work you'll be putting in. Using the information available, you can help figure out a number that meets everyone's needs