The app-antivirus category contains antivirus software.
The app-benchmarks category contains benchmarking software.
The app-emulation category contains emulation software.
The app-office category contains 'office' (word processing, spreadsheets, presentation) software packages.
The app-portage category contains software which works with portage or ebuilds.
The app-text category contains tools for working with human-language text files.
The dev-db category contains libraries and utilities for database related programming.
The dev-dotnet category contains libraries and utilities relevant to the .NET programming environment.
The dev-java category contains libraries and utilities relevant to the Java programming language.
The dev-lang category contains various programming language implementations and related tools.
The dev-libs category contains various miscellaneous programming libraries.
The dev-util category contains various miscellaneous development utilities.
The dev-vcs category contains utilities focused on version control.
The mail-client category contains email clients.
The media-libs category contains media-related libraries.
The media-tv category contains television-related applications.
The net-analyzer category contains network analysis software.
The net-im category contains instant messaging software.
The net-libs category contains libraries that are network-related.
The net-misc category contains various miscellaneous networking tools and utilities.
The sci-electronics category contains electronics packages.
The sys-apps category contains various core system applications, and some non-core system applications which have not yet been moved out into other sys- categories.
The sys-boot category contains bootloaders and related tools.
The sys-devel category contains various core system development tools and libraries.
The sys-fs category contains filesystem tools and utilities.
The sys-kernel category contains kernel source ebuilds and kernel-related tools.
The www-apache category contains modules for the Apache webserver.
The www-client category contains world wide web clients.
The www-servers category contains web server packages.
The x11-base category contains various X11 base implementations.
x11-drivers contain drivers that interface with the core X11 server.