Without estate planning, the state decides who gets your assets (intestate succession), courts appoint a guardian for your children, medical decisions fall to a hierarchy you didn't choose, and the process (probate) is public, slow, and expensive.

The minimum estate planning documents everyone over 18 needs: (1) Will: who gets what, who's guardian for minor children, who executes your wishes. Without one, your state's intestate laws decide — which may not match your preferences. (2) Durable Power of Attorney: who makes financial decisions if you're incapacitated. Without one, your family must petition a court (expensive, slow). (3) Healthcare Power of Attorney / Healthcare Proxy: who makes medical decisions if you can't. (4) Living Will / Advance Directive: what medical interventions you want or don't want (life support, resuscitation, etc.).

Beneficiary designations (on retirement accounts, life insurance, bank accounts) OVERRIDE your will. If your 401(k) beneficiary is an ex-spouse and your will says "everything to my current spouse," the ex-spouse gets the 401(k). Update beneficiary designations after every major life change.

Trusts: a revocable living trust avoids probate (public, 2-6% of estate in fees, 6-18 months), maintains privacy (trusts aren't public record), and allows seamless asset transfer. Cost: $1,500-5,000 one-time setup. For anyone with assets above ~$100K, a trust is likely worth the upfront cost.