1. On UNIX, a home directory can be referenced by using a tilde (~) followed by their login name. For example, "ls ~rob" on my computer will list all the files in "/home/rob". Key point: Web-servers often allow access to user's directories this way. An example would be http://www.robertgraham.com/~rob. Key point: A big hole on the Internet is that people unexpectedly open up information. For example, the file .bash_history is a hidden file in a person's directory that contains the complete text of all commands they've entered into the shell (assuming their shell is bash, which is the most popular one on Linux). From Hacking-Lexicon