Horde is a PHP

PHP

PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...

-based Web application framework

Web application framework

A web application framework is a software framework that is designed to support the development of dynamic websites, web applications and web services. The framework aims to alleviate the overhead associated with common activities performed in Web development...

.

It offers applications such as the Horde IMP email client, a groupware package (calendar, notes, tasks, file manager), a wiki

Wiki

A wiki is a website that allows the creation and editing of any number of interlinked web pages via a web browser using a simplified markup language or a WYSIWYG text editor. Wikis are typically powered by wiki software and are often used collaboratively by multiple users. Examples include...

 and a time and task tracking software.

Horde Email Platform

• IMP
  Internet Messaging Program
  The Internet Messaging Program or IMP is an open source PHP-based webmail client for IMAP. IMP is a component of the Horde project.It is included with cPanel and Plesk installations as a webmail client...
  
   - a web-based email client.
  • MIMP - a stripped down version of IMP for use on devices with a small screen or limited HTML support such as mobile phones, PDAs and others.
• Ingo
  Ingo (software)
  Ingo is an open-source PHP-based mail filter frontend. Ingo is a component of the Horde project....
  
   - an email filter rules manager.
• Sork - a collection of four other Horde modules (accounts, forwards, passwd, and vacation) which together perform various account management functions.

Horde Groupware

• Kronolith - a calendar application.
• Mnemo - a note manager.
• Nag - a multiuser task list manager.
• Turba - a Horde address book / contact manager.

Horde Groupware Webmail Edition

Horde Groupware Webmail Edition extends the Horde Groupware by the Horde e-mail

E-mail

Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...

 applications IMP and Ingo.

Horde Developer Tools

• Chora - a version control repository viewer supporting CVS
  Concurrent Versions System
  The Concurrent Versions System , also known as the Concurrent Versioning System, is a client-server free software revision control system in the field of software development. Version control system software keeps track of all work and all changes in a set of files, and allows several developers ...
  
   and Subversion.
• Whups - the Web Horde User Problem Solver, a ticket-tracking system

Integration into other products

Horde is the web client for the Kolab

Kolab

Kolab is an open source groupware suite. It consists of the Kolab server and a wide variety of Kolab clients, including KDE PIM-Suite Kontact, Horde Webfrontend, Mozilla Thunderbird and Mozilla Lightning with SyncKolab extension and Microsoft Outlook with proprietary Kolab-Connector PlugIns.-Basic...

 groupware system. It is also integrated into the Plesk

Plesk

The Parallels Plesk Panel software package is a commercial web hosting automation program. Originally released under the U.S. company Plesk Inc. and designed in Novosibirsk, Russia, Plesk was acquired by SWSoft in July 2003...

Server management software.