Andrey Andreev wrote:
If you want to install some software without using the Debian package system (for whatever reason), you might want to place it under /opt to avoid messing up your system.
Although, /usr/local is not touched by debian packages for precicely this purpose, and /usr/local/bin is in the default PATH environment variable (unconfirmed, but I'd guess /usr/local/lib was in the default search path for dynamic linking, too)