Lotus Organizer was a personal information manager (PIM). It was initially developed by Threadz, a small British software house, reaching version 3.0. Organizer was subsequently acquired by Lotus Development Corporation, for whom the package was a Windows-based replacement for Lotus Agenda. For several years it was the unquestioned market leader until it was gradually overtaken by Microsoft Outlook. Organizer is notable for using the ″leather-bound personal organizer″ graphical metaphor for its user interface. It is often bundled within Lotus SmartSuite.