When you use APT software management system, you need regularly resynchronize the package index files from their sources. It's normal for skilled admins, but unacceptable for ordinal users. Also It would be desirable to control this synchronization and upgrade system only if nesessary.

Small applet APT Indicator was created as a solution of this problem. It looks like a small icon in notification area of window manager. Icon's picture depends of update status.

Table 1.1. Possible icons

Icon	Description
	There are no new packages available for your system
	Some new packages available. APT looks for security updates by default, and we strongly recommend you to upgrade your system. If you click on icon, you will window with detailed information about new packages.
	Some problems in application or APT. Click on icon, and you will see window with detailed problem description. If you can solve this problem write to Bug Tracking system.
	Applet is receiving index files now. Work still in progress.

This application works under non-privilegy user ,so you need to run external privilege application to upgrade your system. By-default you will run synaptic.