Australia has been traditionally viewed as a relatively egalitarian country, supported by a well-functioning housing system. However, this assessment is facing mounting evidential challenges that are the central concern of this book. This chapter introduces the key concepts and themes used throughout the book. The housing system and housing policy are defined. Housing institutions, interest groups and stakeholders are identified. Analytical concepts that are explained include housing tenure, homelessness, housing need, housing affordability, affordable housing and social housing. The chapter also introduces four exploratory themes that are used throughout the book to generate questions and debate about why and how Australia’s housing system has become more problematic. The chosen themes are international comparison, housing financialisation, the governance of housing policy and housing as a human right.