Siebel Party Concept: Explained in a Simpler Way

As you are already aware that the Party concept in Siebel was introduced with Siebel version 7.
Basic idea behind the Party concept is to overcome the data redundancy. Prior to Party concept, there exist few tables which used to contain the same data but for different reasons resulting in Duplicate data.

Eg:
Earlier the contact and the user formation was stored in two different tables but with party concept the user also became a contact thus avoiding the redundancy

Basic core of RDBMS is to remove data redundancy. Party concept was also introduced to achieve this core idea. Many of the tables were removed and a table called as S_PARTY was introduced.

S_PARTY termed out to be an umbrella for all the persons/groups/orgnization related entities.S_PARTY is the base table and did not store any data but only the relation by means of PARTY_TYPE_CD column. The extension tables of S_PARTY stored all the data.

Eg of S_PARTY extension tables
S_ORG_EXT
S_CONTACT
S_USER
S_BU

The BCs which were based on the S_PARTY extension tables were referred as Party Business Components.