FIRE (Financial Independence, Retire Early).
A definition, in plain English — with the books that teach it.
What it means
A personal-finance movement built on aggressive saving (often 40-70% of income) for 10-20 years to reach financial independence — the point where investment returns cover annual expenses — and optionally retire decades earlier than the traditional retirement age.
Example
The basic FIRE math: if you can live on $40K/year and you have $1M invested at a 4% safe withdrawal rate, you're financially independent. The hard part is getting to the $1M while spending much less than you earn for many years. Variations include LEAN FIRE (extreme frugality, smaller numbers), FAT FIRE (high spending, bigger numbers), Coast FIRE (front-load savings then let compounding take over), and Barista FIRE (work part-time after hitting partial FI). The movement's intellectual roots: The Millionaire Next Door (live below your means), Mr. Money Mustache (extreme frugality), and the 4% safe-withdrawal-rate research from the Trinity Study (1998).
