Definition - What does Directory Traversal mean?
Directory traversal is also known as path traversal, . . / attack (dot dot slash attack), directory climbing and backtracking.
Techopedia explains Directory Traversal
In a directory traversal, the hacker/cracker typically sends in an HTTP request with a series of ../, in order to traverse or climb to a parent directory. The application/server is unable to validate the input data from the Web browser and grants access to the internal and restricted directories and the data they contain. Once the cracker/hacker gains access to the parent directory, he or she can view, edit and delete files, or even execute specific commands.