You can have a salary increase without having any more responsibility, and without being promoted to a higher position. It could be a "cost-of-living increase" which happens when there is economical inflation. The US government decides each year, based on something I don't understand, that money is not worth as much as it was last year, so there has been inflation. There is a formula that economists decide on, and you might get a raise of three percent, one percent, or no raise each year (for example). Also, some companies give you an increase for each year you stay in the company. Your job description would not change in this instance.