Employers will request salary histories and/or requirements to help them determine if there is a fit financially. An employer requests salary requirements to discover what you expect to earn in your next position whereas a request for your salary history is more factual and is specific to information about your past positions; both will be evaluated to determine a potential match. If you ignore either salary request entirely, you are likely to be screened out; on the other hand, you also run the risk of being screened out if you provide specific information too early in the process and the information is not a close fit. Thus, it is best to avoid volunteering salary information; however, you may address salary requests in your cover letter (only when specifically requested). (For more details visit Addressing Requests for Salary Histories or Salary Requirements under Part 2, Cover Letters).
The goal, of course, is to obtain an interview to determine if the position is a fit for you and the company. Unless previously solicited, an interview is where one might expect to discuss salary.