can / may
Ability vs. permission.
Can expresses ability: The intern can read Arabic. May expresses permission or possibility: Members may bring two guests; The ferry may run late in this fog. Can for permission is standard and common: Can I see the floor plans?; Members can bring two guests. Many people still prefer may for asking permission, though, and some of them judge the speaker who asks with can, so May I …? is the safer choice in a job interview or a request to a superior.
Examples
Use Our printer can scan both sides of a page at once. (ability)
Use May I see the floor plans before we sign? (asking permission)