VNC stands for Virtual Network Computing. It is, in essence, a remote display system which allows you to view a computing `desktop' environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures.
SSVNC is two things:
* An enhanced version of the TightVNC client with support for more encodings and color modes, support for x11vnc and UltraVNC extensions, dynamic screen resizing, an improved popup menu, etc.
* A GUI that helps set up an SSL (using stunnel) or SSH tunnel to connect to the VNC server through, as well as forwarding of ports for audio (esound/aRts), SMB, CUPS etc.