A slash (/) is a punctuation mark used for various purposes. Other names for it are: stroke, virgule, diagonal, right-leaning stroke, oblique dash, solidus, slant, separatrix, slake and whack, forward slash. A mark in the reverse direction (\) is called a reverse slash or backslash.
Example: to show how many kilograms of barley are left out of your total supply of barley; 1999/2000.
A slash can also be interpreted as "and". For example, "He is enrolling in the JBA program at Harvard". It can also be interpreted as "or". For example, "Each employee must bring his/her Photo ID". There, the slash (/) means "or".