(1) (Protocol Independent Multicast) A multicast routing protocol endorsed by the IETF. Used in conjunction with an existing unicast routing protocol, it comes in two flavors: Dense Mode (PIM-DM) is used when recipients in the target group are in a concentrated area, while Sparse Mode (PIM-SM) is more efficient when members are scattered. Contrast with DVMRP and MOSPF.

(2) (Personal Information Manager) Software for managing contacts, appointments and tasks. It typically includes a name and address database, calendar, to-do list and note taker. A PIM lets you create text notes for any purpose and retrieve them based on the words in the note. PIMs vary widely, but all attempt to provide a convenient way to manage personal information people use on a daily basis.

Software and Hardware
In the mid-1980s, PIMs emerged both as software for desktop machines and as functions built into handheld electronic organizers. The functions in a PIM are the major features in a PDA. See PDA and smartphone.