IIDs

IIDs is an acronym used in multiple technical domains, and its meaning depends on context. The term often appears in the plural form, but each field has its own established usage.

In probability and statistics, IID stands for independent and identically distributed. The expression i.i.d. describes a collection of random variables that share the same probability distribution and are mutually independent. Some texts refer to multiple such collections informally as IIDs, though the standard abbreviation is i.i.d., and the plural form is not common in formal writing.

In IPv6 networking, IID stands for Interface Identifier. An IPv6 address combines a network prefix with an interface identifier to form a complete address. The IID typically occupies the lower 64 bits of the address and can be generated via methods such as EUI-64 or privacy-preserving randomization. IIDs are used to distinguish interfaces on devices across a network segment and influence address stability and privacy considerations.

In Microsoft COM (Component Object Model), IID means Interface Identifier. An IID is a globally unique identifier (GUID) that identifies a specific interface. Applications use IIDs in queries to request a particular interface via the QueryInterface mechanism. Common examples include IID_IUnknown and IID_IDispatch. IIDs are 128-bit values and are defined in header files as constants or macros.

Overall, IIDs is not a single concept; it represents distinct identifiers whose meaning is determined by the technical domain—statistics, IPv6 addressing, or COM interface identification.