The ile, the Yoruba and Lucumi word for house, is the fundamental unit of Santeria, and the point of the term is that the religion is organised as a household rather than as a public temple.
A household, not a temple
An ile is not a building open to the public but the house of a priest or priestess, into which initiates are brought and around which an extended religious family forms. The consecrated objects of the orishas, the sopera vessels that hold their sacred stones and implements, are kept in the priest home, and the ceremonies, divinations and initiations take place there. Membership is by initiation into the ile, and the priest who initiated a person is that person godparent, so the community is bound by ritual kinship modelled on the family.
Lineage in the diaspora
Because the ile is defined by descent from the priest who founded it and by the line of initiations that runs back through the godparents, the iles form branching lineages, and a member standing is fixed by the house to which they belong. This household structure is what allowed the religion to survive slavery and clandestine practice in Cuba, since it required no public building and could operate within an ordinary home, and it is the same structure that has carried Santeria through its later spread across the Americas. The ile remains the basic cell of the religion, the place where its knowledge is held and transmitted.