/usr directory contains all the user specific programs.It contains the information about the all system user.Created by the System administrator.

/usr is a system directory, see the discussion on /etc vs /usr for more info at http://www.linux.com/learn/answers/view/657-etc-compared-to-usr

It's the search path environment variable PATH that makes programs from various directories available to users. Typical PATH entries include /bin /usr/bin /sbin /usr/sbin /usr/local/bin /opt/SOMEPKG/bin /usr/games $HOME/bin and so on.

Every post above this one is, sadly, wrong.

- /usr is the primary directory for system applications
- /usr does not contain all the user-specific programs (it's neither specifically user-oriented nor specific to individual users)
- /usr contains no information about system users.
- /usr is not created by the sysadmin
- it's not recommended to change icons in /usr/share/icon rather than in a per-user configuration in a user's home directory.

Local additions to the installed programs are often put in /usr/local by the sysadmin if not preconfigured installable is available (say through apt-get or yum).