The term "IFS" can refer to two different things: the Institute for Fiscal Studies and the Internal Family Systems Model.

• Institute for Fiscal Studies: The Institute for Fiscal Studies (IFS) is an economic research institute based in London, United Kingdom, which specializes in UK taxation and public policy. It produces both academic and policy-related findings.

• Internal Family Systems Model: The Internal Family Systems Model (IFS) is an integrative approach to individual psychotherapy developed by Richard C. Schwartz in the 1980s. It combines systems thinking with the view that the mind is made up of relatively discrete subpersonalities, each with its own unique viewpoint and qualities. IFS uses systems psychology, particularly as developed for family therapy, to understand how these collections of subpersonalities are organized. Parts of the mind can take on extreme roles or subpersonalities, but every part has a positive intent, even if its actions are counterproductive and/or cause dysfunction. The IFS method promotes internal connection and harmony to bring the mind back into balance. IFS therapy aims to heal wounded parts and restore mental balance.

Therefore, the answer to the question "what is the IFS?" depends on the context.