adb is part of the adroid development tools and can b found in the directory platform-tools. adb itself must have enough privileges to get a connection to the USB connected android device, so normally it should be started as root.
On an amd64 system the compatibility libs must be installed #
apt-get install ia32-libs
And here is a link to the development platform at google:
http://developer.android.com/sdk/installing.html