Calendaring software is software that minimally provides users with an electronic version of a calendar. Additionally, the software may provide an appointment book, address book, and/or contact list. These tools are an extension of many of the features provided by time management software such as desk accessory packages and computer office automation systems. Calendaring is a standard feature of many PDAs, EDAs, and smartphones.
The software may be a local package designed for individual use (e.g. Lightning extension for Mozilla Thunderbird, Microsoft Outlook without Exchange Server, or Windows Calendar) or may be a networked package that allows for the sharing of information between users (e.g. Mozilla Sunbird, Windows Live Calendar, Google Calendar, or Microsoft Outlook with Exchange Server).