inception event
an Establishment Event that provides the incepting information needed to derive an AID and establish its initial Key state.
Source Sam Smith
An inception event is an establishment key event that represents the creation operation of an
identifier, including its derivation and its initial set of controlling keys as well as other inception
or configuration data for supporting infrastructure.
This is the information needed to derive an AID and establish its initial key-state.
There may be one and only one inception event operation performed on an identifier.
Source KERI Whitepaper
In brief: It's the signed version of a statement containing the inception event with some extra data.
(@henkvancann)
The inception data must include the public key, the identifier derivation from that public key, and may include other configuration data. The identifier derivation may be simply represented by the derivation code. A statement that includes the inception data with attached signature made with the private key comprises a cryptographic commitment to the derivation and configuration of the identifier that may be cryptographically verified by any entity that receives it.
A KERI inception statement is completely self-contained. No additional infrastructure is needed or more importantly must be trusted in order to verify the derivation and initial configuration (inception) of the identifier. The initial trust basis for the identifier is simply the signed inception statement.
(SamMSmith)