This expression, formerly used exclusively in legal documents and business communication, has become acceptable English primarily because it is a convenient saver of time and words. And/or means about the same as each and every and is often equivalent to the simple word or. You can say "boots and/or shoes." You can also say "boots or shoes or both." Purists object to and/or as being awkward and unsightly, but it is permissible in all save fastidious usage.
Dictionary of problem words and expressions. Harry Shaw. 1975.