在网上搜了许久,才发现这篇来自Common Errors in English Usage的在理解上能差强人意.

This is a slash: /. Because the top of it leans forward, it is sometimes called a “forward slash.”

This is a backslash: \. Notice the way it leans back, distinguishing it from the regular slash.

Slashes are often used to indicate directories and subdirectories in computer systems such as Unix and in World Wide Web addresses. Unfortunately, many people, assuming “backslash” is some sort of technical term for the regular slash, use the term incorrectly, which risks confusing those who know enough to distinguish between the two but not enough to realize that Web addresses rarely contain backslashes.
 另外在具体的用途上这们归纳下比较好:
正斜杠/slash 表示除法，分隔。在windows系统中通常用来分隔命令行参数，/表示选项等。不能作为文件名。
而在unix系统中，/表示目录。由于web遵循unix命名，所以在网址（URL）中，/表示目录。
反斜杠ackslash，在windows系统中用来表示目录。